Lactarius subgenus Russularia (Russulaceae) in South-East Asia: 3. new diversity in Thailand and Vietnam

Abstract

Lactarius subgenus Russularia is a dominant group of milkcaps in Southeast Asia. This paper reveals the large diversity of the subgenus, with eight new species and one known species being described from montane evergreen and coniferous forests. All new species are supported by both morphological and molecular data, the latter using Maximum likelihood and Bayesian analysis based on the ITS region. Complete macro-and micro-morphological descriptions and illustrations are given. A key to the new taxa is provided. Lactarius chichuensis is reported for the first time from Thailand.

Full text

Phytotaxa 207 (3): 215–241
www.mapress.com/phytotaxa/
Copyright © 2015 Magnolia Press Article PHYTOTAXA
ISSN 1179-3155 (print edition)
ISSN 1179-3163 (online edition)
Accepted by Genevieve Gates: 18 Apr. 2015; published: 11 May 2015
http://dx.doi.org/10.11646/phytotaxa.207.3.1
215
Lactarius subgenus Russularia (Russulaceae) in South-East Asia: 3. new diversity
in Thailand and Vietnam
KOMSIT WISITRASSAMEEWONG1,2,3, JORINDE NUYTINCK4, HUYEN THANH LE5, ESKE DE CROP3, FELIX
HAMPE3, KEVIN D HYDE1,2 & ANNEMIEKE VERBEKEN3
1Institute of Excellence in Fungal Research, Mae Fah Luang University, 333 Moo 1, Thasud sub-district, Muang district, Chiang Rai
57100, Thailand, E-mail: Komsit.Wisitrassameewong@UGent.be (corresponding author)
2School of Science, Mae Fah Luang University, 333 Moo 1, Thasud sub-district, Muang district, Chiang Rai 57100, Thailand
3Research Group Mycology, Department of Biology, Gent University, K.L. Ledeganckstraat 35, 9000 Gent, Belgium
4Naturalis Biodiversity Center, Section National Herbarium of the Netherlands, P.O. Box 9517, 2300RA Leiden, The Netherlands
5Faculty of Environment, Hanoi University of Natural Resources and Environment, 41A Street K1, Cau Dien, Tu Liem, Hanoi, Vietnam
Abstract
Lactarius subgenus Russularia is a dominant group of milkcaps in Southeast Asia. This paper reveals the large diversity
of the subgenus, with eight new species and one known species being described from montane evergreen and coniferous
forests. All new species are supported by both morphological and molecular data, the latter using Maximum likelihood and
Bayesian analysis based on the ITS region. Complete macro- and micro-morphological descriptions and illustrations are
given. A key to the new taxa is provided. Lactarius chichuensis is reported for the first time from Thailand.
Keywords: Russulales, identification, ectomycorrhizal fungi, biodiversity
Introduction
Tropical Southeast Asia is recognized as one of the world’s biodiversity hotspots and contains a high concentration of
endemic species (Myers et al. 2000). The high number of endemic plants includes several families of ectomycorrhizal
trees (e.g. Dipterocarpaceae, Fagaceae, Betulaceae, and Pinaceae). However, biodiversity is strongly declining in
Southeast Asia due to deforestation for urbanization, logging, and agricultural expansion by local people and agricultural
companies, who clear vast areas for crop cultivation (Sodhi et al. 2010). Since ectomycorrhizal (ECM) fungi are
obligate symbionts of ECM trees and shrubs, an inevitable consequence of forest logging is the loss of ECM species,
including those belonging to the genus Lactarius Pers. Issues regarding forest logging have therefore become of great
concern in many countries (Mortimer et al. 2012).
Mycorrhizal trees have been used for reforestation programs in many regions such as tropical Africa, South
America and Southeast Asia. Thus many attempts used mycorrhizal symbionts to improve the reforestation performance
of transplanted mycorrhizal trees (Bâ et al. 2009, Ergiles et al. 2009, Sanon et al. 2010, Aggangan et al. 2012). Since
ECM fungi facilitate water and nutrient uptake for their host plants, they are considered as microorganisms that can
promote plant growth in forests. There is little information regarding the use of Lactarius species in tree seedling
production. Lactarius deliciosus (L.: Fr.) Gray appears to be the most used Lactarius species applied to improve
seedling establishment of Pinus trees (Guerin-Laguette et al. 2003, Parladé et al. 2004, Diaz et al. 2009). Our research
aims at exploring the biodiversity of Lactarius subgenus Russularia (Fr.) Kauffman in Southeast Asia, as in local
ecosystems it is one of the dominant groups in terms of numbers of basidiocarps covering the forest floor.
Lactarius subgenus Russularia is one of the three major subgenera of Lactarius. Species traditionally placed in
this subgenus are recognized by basidiomata which are typically dry and vary in color from orange to warm brown
(Heilmann-Clausen et al. 1998). As mentioned in Wisitrassameewong et al. (2014b), it is remarkable that most taxa
in this group have unchanging latex and that the group as a whole is characterized by few color changes in the latex
as compared to the other subgenera of Lactarius and Lactifluus (which together form the large group of milkcaps).
Some species are described as having white to pale yellow latex e.g. L. quietus (Fr.: Fr.) Fr., and L. decipiens Quél.

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216 • Phytotaxa 207 (3) © 2015 Magnolia Press
Lactarius tabidus Fr. has white latex which slowly turns straw yellow, while L. duplicatus A.H. Sm. has white latex
that becomes sulphur yellow (Heilmann-Clausen et al. 1998). In the Northern hemisphere, this group is well-studied in
Europe (Heilmann-Clausen et al. 1998, Basso 1999), North America (Hesler & Smith 1979) and Japan (Hongo 1957a,
b, 1971).
Many mycological excursions have focused on milkcap diversity (both Lactarius and Lactifluus) in Southeast
Asia in the last decade (Le et al. 2007a, 2007b, 2007c, Stubbe et al., 2007, 2008, Van de Putte et al. 2010, Verbeken
et al. 2014, Wisitrassameewong et al. 2014a, 2014b). Compared to the exploration rate between L. subg. Russularia
and other groups of milkcaps, the exploration rate in Russularia-group is quite low. So far about 21 known species
belonging to L. subg. Russularia have been reported, including also eleven species from Papua New Guinea and
Indonesia for which we are still missing molecular data. We need a comprehensive contribution to show the diversity
of L. subg. Russularia for this subcontinent. This paper contributes to the knowledge of the biodiversity of the subgenus
in Thailand and Vietnam. Only one significant contribution to milkcap diversity in Vietnam is given by Morozova et
al. (2013) but that was on two new species of Lactifluus, therefore this will be the first report of Lactarius subgenus
Russularia for the country. We collected specimens mainly from montane evergreen forests dominated by Fagaceae
and coniferous forests dominated by Pinus kesiya Royle ex Gordon from Northern Thailand and Southern Vietnam.
The aim was to use both morphological and molecular tools to reveal the diversity of this ectomycorrhizal group in
order to stress their importance when it comes to conservation of the whole ecosystem.
Materials and methods
Taxon sampling
Fresh basidiomata were gathered in montane rainforests and planted coniferous forests in Northern Thailand and
the regions around Dalat in Vietnam by the first author. Some collections were made by Huyen Thanh Le and Eske
De Crop. The studied materials are deposited in the herbarium Universitatis Gandavensis (GENT), Belgium; Mae
Fah Luang University herbarium (MFLU) and Chiang Mai University (CMU), Thailand; and/or San Francisco State
University (SFSU), USA.
Morphological study
Macromorphological characters were observed on fresh material. Specimens were described and photographed in fresh
condition during daylight hours. Color coding is according to Kornerup and Wanscher (1978). Macro-morphological
features of the basidiocarp were documented in term of size, shape and features of pileus, lamellae and stipe. Latex
features were tested by recording color when the latex was immediately exposed to the air, color change after exposing
to the air for a certain time, color change when a drop of latex tested with 10% KOH and color change when a drop of
latex touched on white tissue paper and a white cotton handkerchief. For morphological terminology, we refer to Vellinga
(1988) and to Verbeken (1996) and Heilmann-Clausen et al. (1998) particularly for pileipellis structures. Microscopic
features were studied from dried material, mainly in Congo Red in L4 (Clémençon 1973). Basidiospores were observed
in Melzer’s reagent. Basidia were measured excluding sterigmata length. The spore measurement included at least 20
spores from each collection, and excludes the ornamentation. Basidiospore measurements are represented as {(MIN)
[AVa-2×SD]−AVa–AVb−–[AVb+2×SD] (MAX)} length × {(MIN) [AVa-2×SD]–AVa–AVb−[AV+2×SD] (MAX)}
width, in which MIN = the minimum value, MAX = the maximum value, AVa = lowest mean value for the measured
collection, AVb = highest mean value for the measured collection and SD = standard deviation. Q corresponds to spore
“length/width ratio” and is given as (MINQa) Qa–Qb (MAXQb), where Qa and Qb are the lowest and the highest mean
ratio for a measured specimen, respectively. All line drawings were made by Komsit Wisitrassameewong (KW).
DNA extraction, PCR amplification, DNA sequencing
Genomic DNA was extracted from fresh material stored in 2×CTAB buffer using the protocol described by Nuytinck
& Verbeken (2003) with the modifications described in Van de Putte et al. (2010). The internal transcribed spacer of
the nuclear ribosomal DNA (ITS) was amplified and sequenced using the ITS1-F and ITS4 primers (White et al. 1990,
Gardes & Bruns 1993). Sequencing was conducted with an ABI 3730XL or ABI 3700 by MACROGEN (Amsterdam,

LACTARIUS SUBGENUS RUSSULARIA IN SOUTH-EAST ASIA Phytotaxa 207 (3) © 2015 Magnolia Press • 217
the Netherlands). Obtained sequences were assembled and edited with the software SequencerTM v5.0 (Gene Code
corporation, Ann Arbor, Michigan, U.S.A.).
Nucleotide alignment and phylogenetic reconstruction
This study comprises the DNA sequence data of most European and Southeast Asian representatives of L. subg.
Russularia, most of which were generated from GENT. Additional sequences of European species were obtained from
GenBank and UNITE. We included all European representatives except L. duplicatus A.H. Sm. The sequences of
North American taxa, L. rubidus (Hesler & A.H. Sm.) Methven, L. subserifluus Longyear and L. strigosipes Montoya
& Bandala were retrieved from GenBank. Representatives belonging to the other subgenera of Lactarius were included
in the analysis. Three species of L. subgenus Plinthogalus (Berk.) Hesler & A.H. Sm., L. pterosporus Romagn., L.
fuliginosus Romagn. and L. friabilis H.T. Le & Stubbe, were used as the outgroup in the phylogeny. Table 1 shows an
overview of all sequences used in the phylogenetic analysis. Nucleotide sequence alignment was made using MAFFT
v7 (Katoh & Standley 2013) and later manually edited in MEGA6 (Tamura et al. 2013). The program Gblocks v0.91b
(Castresana 2000) was used to eliminate poorly aligned positions in the alignment, with settings allowing gaps within
selected blocks, smaller blocks (minimum 5 bp) and bigger segments with contiguous non-conserved positions
(maximum 10 bp). The Alignment Transformation Environment (ALTER) was used to convert sequence alignment
formats (Glez-Peña et al. 2010). RAxML v7.0.3 (Stamatakis 2006) was used to infer the maximum likelihood
(ML) topology, applying the Rapid Bootstrapping algorithm for 1000 replicates using the GTRGAMMA model. To
determine the model of character evolution of each gene partition, we used MrModeltest v2.3 (Nylander 2004) and the
suggested parameters were applied for Bayesian inference (BI) analysis. Four separate runs in parallel with 10 million
Markov chain Monte Carlo (MCMC) generations were executed using MrBayes v3.1.2 (Ronquist & Huelsenbeck
2003). Sample frequency was set at 100. To recognize that the number of generations was sufficient, we looked for
a stationary likelihood graph and the effective sample size (ESS) value (should exceed 200) from independent runs
using the graphing function in Tracer v1.6 (Drummond & Rambaut 2007). The proper burn-in value for the dataset was
observed using this program. All phylograms were displayed using FigTree v1.3.1 (Rambaut 2009).
TABLE 1: List of specimens and GenBank accession number of sequences used in the phylogenetic analyses.
Species Voucher collection Origin ITS accession no.
Lactarius subg. Russularia Lactarius subg. Russularia
L. rubrobrunneus sp. nov. AV12-044 (GENT, MFLU) (Type) Thailand KF432985 L. rubrobrunneus sp. nov.
L. rubrobrunneus sp. nov. LTH334 (GENT, CMU, SFSU) Thailand KR025598 L. rubrobrunneus sp. nov.
L. rubrobrunneus sp. nov. LTH149 (GENT, CMU, SFSU) Thailand KR025599 L. rubrobrunneus sp. nov.
L. fuscomaculatus sp. nov. KW111 (GENT, MFLU) Thailand KF433021 L. fuscomaculatus sp. nov.
L. fuscomaculatus sp. nov. KW112 (GENT, MFLU) Thailand KR025602 L. fuscomaculatus sp. nov.
L. fuscomaculatus sp. nov. KW128 (GENT, MFLU) Thailand KR025601 L. fuscomaculatus sp. nov.
L. fuscomaculatus sp. nov. KW370 (GENT, MFLU) Thailand KR025600 L. fuscomaculatus sp. nov.
L. fuscomaculatus sp. nov. KW373 (GENT, MFLU) (Type) Thailand KR025603 L. fuscomaculatus sp. nov.
L. austrorostratus sp. nov. KW108 (GENT, MFLU) (Type) Thailand KF433012 L. austrorostratus sp. nov.
L. austrorostratus sp. nov. KW109 (GENT, MFLU) Thailand KF433013 L. austrorostratus sp. nov.
L. austrorostratus sp. nov. KW110 (GENT, MFLU) Thailand KF433014 L. austrorostratus sp. nov.
L. rubrocorrugatus sp. nov. KW453 (GENT, MFLU) Thailand KR025592 L. rubrocorrugatus sp. nov.
L. rubrocorrugatus sp. nov. KW042 (GENT, MFLU) Vietnam KF433010 L. rubrocorrugatus sp. nov.
L. rubrocorrugatus sp. nov. KW043 (GENT, MFLU) Vietnam KR025589 L. rubrocorrugatus sp. nov.
L. rubrocorrugatus sp. nov. KW045 (GENT, MFLU) Vietnam KR025591 L. rubrocorrugatus sp. nov.
L. rubrocorrugatus sp. nov. KW123 (GENT, MFLU) Thailand KR025588 L. rubrocorrugatus sp. nov.
L. rubrocorrugatus sp. nov. KW294 (GENT, MFLU) Thailand KF433011 L. rubrocorrugatus sp. nov.
L. rubrocorrugatus sp. nov. KW384 (GENT, MFLU) (Type) Thailand KR025590 L. rubrocorrugatus sp. nov.
L. rubrocorrugatus sp. nov. EDC14-505 (GENT, MFLU) Thailand KR025587 L. rubrocorrugatus sp. nov.
L. aquosus sp. nov. LTH262 (GENT, CMU, SFSU) Thailand KR025622 L. aquosus sp. nov.
L. aquosus sp. nov. KW231 (GENT, MFLU) (Type) Thailand KF432984 L. aquosus sp. nov.
L. tangerinus sp. nov. KW091 (GENT, MFLU) Thailand KR025626 L. tangerinus sp. nov.
L. tangerinus sp. nov. LTH203 (GENT, CMU, SFSU)
(Type)
Thailand KR025627 L. tangerinus sp. nov.
L. tangerinus sp. nov. EDC14-475 (GENT) Thailand KR025625 L. tangerinus sp. nov.
......continued on next page

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218 • Phytotaxa 207 (3) © 2015 Magnolia Press
TABLE 1. (Continued)
Species Voucher collection Origin ITS accession no.
L. inconspicuus sp. nov. KW339 (GENT, MFLU) (Type) Thailand KR025584 L. inconspicuus sp. nov.
L. inconspicuus sp. nov. KW100 (GENT, MFLU) Thailand KF433001 L. inconspicuus sp. nov.
L. inconspicuus sp. nov. KW003 (GENT, MFLU) Thailand KR025583 L. inconspicuus sp. nov.
L. inconspicuus sp. nov. LTH256 (GENT, CMU, SFSU) Thailand KF433003 L. inconspicuus sp. nov.
L. inconspicuus sp. nov. LTH098 (GENT, CMU, SFSU) Thailand KF433004 L. inconspicuus sp. nov.
L. kesiyae sp. nov. KW034 (GENT, MFLU) Vietnam KF432995 L. kesiyae sp. nov.
L. kesiyae sp. nov. AV12-022 (GENT, MFLU) Thailand KR025618 L. kesiyae sp. nov.
L. kesiyae sp. nov. KW427 (GENT, MFLU) Thailand KR025614 L. kesiyae sp. nov.
L. kesiyae sp. nov. KW346 (GENT, MFLU) Thailand KF432993 L. kesiyae sp. nov.
L. kesiyae sp. nov. KW033 (GENT, MFLU) Vietnam KF432994 L. kesiyae sp. nov.
L. kesiyae sp. nov. KW219 (GENT, MFLU) Thailand KR025616 L. kesiyae sp. nov.
L. kesiyae sp. nov. KW210 (GENT, MFLU) Thailand KR025617 L. kesiyae sp. nov.
L. kesiyae sp. nov. KW036 (GENT, MFLU) Vietnam KR025620 L. kesiyae sp. nov.
L. kesiyae sp. nov. KW224 (GENT, MFLU) Thailand KR025615 L. kesiyae sp. nov.
L. kesiyae sp. nov. KW032 (GENT, MFLU) (Type) Vietnam KR025619 L. kesiyae sp. nov.
L. sublaccarioides KW300 (GENT, MFLU) (Type) Thailand KF432996 L. sublaccarioides
L. sublaccarioides KW323 (GENT, MFLU) Thailand KF432997 L. sublaccarioides
L. sublaccarioides KW332 (GENT, MFLU) Thailand KF432998 L. sublaccarioides
L. camphoratus AV10-40 (GENT) Norway KF432971 L. camphoratus
L. camphoratus JV2006-20 (GENT) Belgium KR025610 L. camphoratus
L. subumbonatus JKLAC110902 (GENT) Germany KR025596 L. subumbonatus
L. subumbonatus RC-KVP10-002 (GENT) Belgium KF432981 L. subumbonatus
L. subumbonatus EDC11-237 (GENT) Belgium KR025595 L. subumbonatus
L. serifluus JV2006-028 (GENT) Belgium KR025597 L. serifluus
L. crenulatulus KW125 (GENT, MFLU) Thailand KR025605 L. crenulatulus
L. crenulatulus KW368 (GENT, MFLU) Thailand KJ458979 L. crenulatulus
L. crenulatulus KW383 (GENT, MFLU) (Type) Thailand KR025604 L. crenulatulus
L. pasohensis KW355 (GENT, MFLU) Thailand KF432988 L. pasohensis
L. pasohensis DS06-231 (GENT, KEP) Malaysia KF432987 L. pasohensis
L. pasohensis DS06-245 (GENT, KEP) (Type) Malaysia KF432986 L. pasohensis
L. perparvus KW320 (GENT, MFLU) (Type) Thailand KJ458981 L. perparvus
L. perparvus KW337 (GENT, MFLU) Thailand KJ458982 L. perparvus
L. glabrigracilis KW093 (GENT, MFLU) (Type) Thailand KR025606 L. glabrigracilis
L. glabrigracilis KW335 (GENT, MFLU) Thailand KJ458985 L. glabrigracilis
L. glabrigraclis KW321 (GENT, MFLU) Thailand KR025607 L. glabrigraclis
L. rubidus M.Kuo 01131106 (NY) USA KC691205 L. rubidus
L. laccarioides KW336 (GENT, MFLU) (Type) Thailand KF432991 L. laccarioides
L. laccarioides KW360 (GENT, MFLU) Thailand KF432992 L. laccarioides
L. atlanticus LAC11121201 (GENT) Spain KF432976 L. atlanticus
L. atlanticus JKLAC13122801 (GENT) Portugal KR025611 L. atlanticus
L. atlanticus AV13-047 (GENT) Italy KR025612 L. atlanticus
L. subserifluus JMP0046 USA EU819486 L. subserifluus
L. strigosipes Mexico JN003629 L. strigosipes
L. gracilis KW096 (GENT, MFLU) Thailand KR025609 L. gracilis
L. gracilis KW354 (GENT, MFLU) Thailand KR025608 L. gracilis
L. gracilis KW334 (GENT, MFLU) Thailand KF433017 L. gracilis
L. hirtipes XHW1243 (HKAS) China KF433007 L. hirtipes
L. chichuensis XHW1236 (HKAS) China KF475766 L. chichuensis
L. chichuensis KW271 (GENT, MFLU) Thailand KR025593 L. chichuensis
L. chichuensis KW012 (GENT, MFLU) Thailand KF433008 L. chichuensis
L. chichuensis KW359 (GENT, MFLU) Thailand KF433009 L. chichuensis
L. chichuensis KW421 (GENT, MFLU) Thailand KR025594 L. chichuensis
L. rostratus 691(MUVE) Italy JF908276 L. rostratus
L. falcatus KVP08-038 (GENT) (Type) Thailand KF133262 L. falcatus
L. quietus JN2012-040 (GENT) Germany KR025623 L. quietus
L. quietus KW131 (GENT) Belgium KF432972 L. quietus
L. quietus KW133 (GENT) Belgium KR025624 L. quietus
......continued on next page

LACTARIUS SUBGENUS RUSSULARIA IN SOUTH-EAST ASIA Phytotaxa 207 (3) © 2015 Magnolia Press • 219
TABLE 1. (Continued)
Species Voucher collection Origin ITS accession no.
L. omphaliformis PAM08083009 France HQ714719 L. omphaliformis
L. lacunarum JKLAC11092901 (GENT) Germany KF432982 L. lacunarum
L. lacunarum EDC11-231 (GENT) Belgium KR025570 L. lacunarum
L. lacunarum JKLAC13122201 (GENT) Portugal KR025569 L. lacunarum
L. tabidus KW130 (GENT) Belgium KR025582 L. tabidus
L. tabidus IMN98142 France KR025581 L. tabidus
L. aurantiacus JN11-089 (GENT) Greece KR025580 L. aurantiacus
L. aurantiacus JN2001-60 (GENT) Slovakia KF432974 L. aurantiacus
L. lanceolatus IA-F20 Norway UDB002454 L. lanceolatus
L. brunneohepaticus PAM08090315 France HQ714726 L. brunneohepaticus
L. obscuratus ED2008-15 (GENT) USA KR025579 L. obscuratus
L. obscuratus LVL02-006 (GENT) Belgium KF432978 L. obscuratus
L. cyathuliformis UE04.09.2004-2 (UPS) Sweden KF133266 L. cyathuliformis
L. hepaticus JN02-049 (GENT) Belgium KF432980 L. hepaticus
L. hepaticus JV2006-025(GENT) Belgium KR025574 L. hepaticus
L. hepaticus JV2006-021 (GENT) Belgium KR025573 L. hepaticus
L. hispanicus MA-Fungi 53339 Spain AJ555567 L. hispanicus
L. fulvissimus JN2012-025 (GENT) Germany KR025576 L. fulvissimus
L. fulvissimus JV2006-006 (GENT) Belgium KR025577 L. fulvissimus
L. borziana Switzerland AF373599 L. borziana
L. rubrocinctus EDC12-210 (GENT) Germany KF432977 L. rubrocinctus
L. rubrocinctus JKLAC10082201 (GENT) Germany KR025575 L. rubrocinctus
L. sphagneti JKLAC11091502 (GENT) Germany KF432975 L. sphagneti
L. badiosanguineus AV04-235 (GENT) France KF432983 L. badiosanguineus
L. badiosanguineus AV10-44 (GENT) Norway KR025578 L. badiosanguineus
L. decipiens VDKO882 (GENT) Belgium KR025586 L. decipiens
L. decipiens AV2000-137 (GENT) Italy KF432973 L. decipiens
L. decipiens AV13-044 (GENT) Italy KR025585 L. decipiens
L. subdulcis ED2008-27 (GENT) Belgium KR025572 L. subdulcis
L.subdulcis JN2012-020 (GENT) Germany KR025571 L.subdulcis
L. subg. Lactarius L. subg. Lactarius
L. austrozanarius FH12-007 (GENT, MFLU) Thailand KF432965 L. austrozanarius
L. purpureus FH12-008 (GENT, MFLU) Thailand KF432966 L. purpureus
L. scrobiculatus JN01-058 (GENT) Slovakia KF432968 L. scrobiculatus
L. hatsudake JN2011-065 (GENT) Vietnam KF432967 L. hatsudake
L. tornimosus JN11-086 (GENT) Greece KR025613 L. tornimosus
L. subg. Plinthogalus L. subg. Plinthogalus
L. fuliginosus MTB97-24 (GENT) Sweden JQ446111 L. fuliginosus
L. pterosporus DS09-614 (GENT) Italy KR025628 L. pterosporus
L. friabilis FH12-103 (GENT, MFLU) Thailand KF432961 L. friabilis
Results
Phylogeny
The ITS multiple sequence alignment consists of 119 sequences and 1099 bases (including gaps). Gblocks retained
76% of the original sequence alignment; the excluded regions comprising about 257 bases, which mostly are at the
beginning and the end of the multiple sequence alignment. The excluded regions of this study are largely due to the
length variability of sequences available in GenBank. Twenty three, ten and three known Russularia species from
Europe, Asia and North America respectively are included in the study. Figure 1 shows the ML topology based on the
ITS sequence alignment. The bootstrap values (BS) and posterior probabilities (PP) are indicated in the phylogram
when BS and PP exceed 50 and 0.85, respectively. All new species are indicated in boldface. Taxa in blue are obtained
from public databases. Based on ITS sequence data, taxa from L. subg. Russularia form a monophyletic group apart
from L. subg. Lactarius, but with low bootstrap support (48%). Except for Indonesian and Papuan representatives
from Verbeken et al. (2001) and Verbeken & Horak (2000), we gathered all known Southeast Asian representatives

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220 • Phytotaxa 207 (3) © 2015 Magnolia Press
here and the molecular evidence shows that all newly proposed ones are new species. They are well-delimited in subg.
Russularia (Figure 1).
FIGURE 1. The obtained ML phylogeny based on ITS sequences. Names in boldface are new species. Names in blue are obtained from
public databases. Bootstrap values and posterior probabilities are indicated if they exceed 50% and 0.85, respectively. The bar scale
represents the expected number of nucleotide changes per site.

LACTARIUS SUBGENUS RUSSULARIA IN SOUTH-EAST ASIA Phytotaxa 207 (3) © 2015 Magnolia Press • 221
Taxonomy
Lactarius aquosus H.T. Le & K.D. Hyde, sp. nov. (Figure 2 and 11a)
FIGURE 2. L. aquosus: a. basidiospore, b. pleuromacrocystidia, c. basidia, d. cheilocystidia, e. marginal cell, f. pseudocystidia, g.
pileipellis (a−g: KW231, holotype) (scale bar = 10 µm).

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MycoBank number: MB811741; Facesoffungi number: FoF00634
Diagnosis: a medium-sized species with a smooth cap surface which is zonate, brown to orange-brown coloration
and a paler margin, transparent latex, completely transparent, incompletely to almost completely reticulate basidiospores,
protruding pleuromacrocystidia and a cutis as pileipellis.
Etymology:—‘aquosus’ is referring to the transparent latex.
Typus:—THAILAND, Chiang Mai Province, Mae-on district, Mae Takraii National Park, Thepsaded Waterfall,
alt. 1150 m , N18º55.32 E99º21.31, 01/06/2012, KW231 (holotype, GENT!, isotype, MFLU!).
Basidiocarps medium-sized. Pileus 21−37 mm diam., rather plane with depressed center to infundibuliform at
maturity, typically darker colored in center and appearing more or less zonate near the margin; surface smooth, dry and
glossy in moist condition, reddish brown (8E8) in center, reddish blond (5C4) to dark blond (5D4) to reddish brown
(8D5), margin pale orange (5A3) to cream colored margin with short and inconspicuous striations, slightly crenulate.
Lamellae subdecurrent to decurrent, 1−4.5 mm broad, crowded, with 2−4 series of lamellulae, cream to yellowish
white (4A1−2) to light yellow (4A4), with light brown (7D6) discolorations in older specimens, yellowish brown
(5D5) when bruised. Stipe 25−48 ×5−15 mm, cylindrical, hollow; surface smooth, rugose when old, often with short
hairs and whitish pruinose at base, brownish orange (6C6) to light brown (6−7D6), darkening to brown (7E7) near
base. Context 2−4.5 mm broad in pileus, pale yellow (3A3) to grayish yellow (3B4) to light grayish orange (6B−C4),
unchanging when cut; smell strong, raphanoid; taste mild or slightly bitter and astringent. Latex watery, unchanging on
exposure, moderately abundant, unchanging with 10 % KOH, unchanging on white tissue paper and on white cotton
handkerchief. Macrochemical reaction no reaction on the context with 10 % KOH and with FeSO4.
Basidiospores subglobose to broadly ellipsoid, 6.1−6.9−7.2−7.9(−8.0) × 5.4−5.9−6.2−6.9 µm; Q = 1.06−1.15−
1.17−1.27 (n=60); ornamentation amyloid, composed of ridges up to 1 µm high, forming an incomplete to almost
complete reticulum, with short ridges connected by finer lines which are blunt to subacute; isolated warts common;
plage inamyloid. Basidia 48−52 × 12−16 µm, 4-spored, subclavate, sometimes bent near base, typically with needle-
like to guttate contents. Pleuromacrocystidia 55−74 × 9−16 µm, abundant, subfusiform to subclavate with mucronate
or moniliform apex, protruding up to 30 µm, with fine granules and needle-like contents. Pleuropseudocystidia 3−4
µm diam., not emergent, irregularly cylindrical, bent or curved near base; apex round or capitate. Lamellar edge
heterogeneous, consisting of basidia, capitate to subclavate marginal cells 27−38 × 12−17 µm and cheilocystidia
34−58 × 8−14 µm, abundant, subfusiform, some irregularly curved, with mucronate to slightly moniliform apex,
protruding up to 35 µm above the hymenium. Lamellar trama consisting of smaller and larger globose cells, septate
hyphae and lactiferous hyphae. Pileipellis a cutis, 90−140 µm thick, consisting of parallel, repent and sometimes
slightly erect hyphae.
Habitat: gregarious or scattered on slope, in montane tropical forest, with Fagaceae.
Collections examined: THAILAND, Chiang Mai Province, Mae-on district, Mae Takraii National Park, Thepsaded
Waterfall, alt. 1150 m, N18º55.32 E99º21.31, 01/06/2012, KW231 (holotype, GENT!, isotype, MFLU!); Chiang Mai
province, Mae Teang district, Bahn Pha Deng village, alt. 900 m., N19º17.12 E98º44.00, 01/06/2004, LTH102 (GENT!,
CMU!, SFSU!);—ibid. 05/06/2005, LTH262 (GENT!, CMU!, SFSU!).
Comments: Lactarius aquosus is easily recognized in the field by its smooth pileus surface, zonate cap and
transparent latex. Microscopically, this species has incompletely reticulate basidiospores and a cutis as a pileipellis.
Lactarius austrorostratus Wisitrassameewong & Verbeken, sp. nov. (Figure 3)
MycoBank number: MB811742; Facesoffungi number: FoF00635
Diagnosis: a medium sized, reddish brown species, with incompletely reticulate basidiospore ornamentation in a
zebroid pattern, rostrate pleuromacrocystidia and a hyphoepithelium as a pileipellis.
Etymology:—‘austrorostratus’ refers to the occurrence in South East Asia and the rostrate cystidia.
Typus:—THAILAND, Chiang Mai province, Jomthong district, Bahn Luang sub-district, Doi Inthanon, nature
trail at highest spot, N18º35.20 E98º29.03, alt. 2565 m, 06/07/2011, KW108 (holotype, GENT!, isotype, MFLU!).
Pileus: 10−30 mm diameter, at first convex to broadly convex with incurved margin, later expanding and with
a more depressed center, or slightly infundibuliform, papillate in center; surface smooth when young, then becoming
rugulose, particularly in center, dark brown (9F7) initially, turning dark brown (9F6−7) to reddish brown (9E8); margin
inflexed, short striation, crenulate. Lamellae 1−3 mm broad, crowded, with 1−2 series of lamellulae, subdecurrent,
cream to dark cream; edge minutely crenulate. Stipe 30−43 × 4 mm, cylindrical, central to slightly eccentric, fragile,
fistulose; surface wrinkled, reddish brown (8D7) to dark brown (7F6) at base in youth, turning darker brown (8F8)
when mature. Context 0.5−2 mm broad, fragile, pale reddish brown, unchanging when cut; odor like L. quietus or

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Pentatomidae bugs, taste mild. Latex somewhat watery white to whey-like, sparse to moderately abundant, unchanging
on exposure, unchanging with 10% KOH, unchanging on white tissue paper and on white cotton handkerchief, taste
mild. Macrochemical reaction no reaction on the context with 10 % KOH and with FeSO4.
FIGURE 3. L. austrorostratus: a. basidiospore, b. pleuromacrocystidia, c. pseudocystidia, d. basidia, e. marginal cell, f. cheilocystidia, g.
pileipellis (a and g: KW109, b−f: KW108, holotype) (scale bar = 10 µm).
Basidiospores subglobose to ellipsoid, (6.1−)6.4−7.1−7.8 ×(5.6−)5.7−6.2−6.8(−6.9) µm; Q = 1.07−1.14−1.15−1.30,

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(n = 40); ornamentation amyloid, up to 1 µm high, consisting of blunt irregular ridges, forming an incomplete
reticulum, at times with a zebroid aspect; isolated warts abundant; plage distally amyloid. Basidia 34−52 × 10−17
µm, mostly 4-spored, sometimes 1-or 2-spored, irregularly subclavate, some irregularly cylindrical, with guttate
contents and fine granules. Pleuromacrocystidia abundant, 54−107 × 9−18 µm, lanceolate to subfusiform, somewhat
slender, protruding up to 40 µm, rostrate apex, often tortuous particularly near the apex, mostly with refractive contents
containing fine granules. Pleuropseudocystidia abundant, 3−6 µm diam., cylindrical, but tortuous near the base, with
fine granules, needle-like contents and sometimes with crystalline contents. Lamellar edge sterile, with marginal cells
and cheilocystidia; marginal cells 13−26 × 8−18 µm, clavate to obovoid; cheilocystidia 32−58 × 10−16 µm, scattered
to abundant, subfusiform with mucronate to rounded apex, with refractive contents containing fine granules, protruding
up to 15 µm. Lamellar trama consisting of smaller and larger globose cells, septate hyphae and lactiferous hyphae.
Pileipellis a hyphoepithelium, suprapellis a thin layer of repent hyphae; subpellis about 60−80 µm thick, consisting of
large globose cells which are up to 35 µm diam.
Habitat: solitary or gregarious on ground in evergreen rainforest, under Castanopsis.
Collections examined: THAILAND, Chiang Mai province, Jomthong district, Bahn Luang sub-district, Doi
Inthanon, nature trail at highest spot, N18º35.20 E98º29.03, alt. 2565 m, 06/07/2011, KW108 (holotype, GENT!,
isotype, MFLU!);−ibid., 06/07/2011, KW109 (GENT!, MFLU!);−ibid., 06/07/2011, KW110 (GENT!, MFLU!).
Comments: This species is in some aspects similar to L. rostratus, e.g. in basidiocarp size, color and latex features.
Both species have rostrate pleuromacrocystidia but the Asian species has larger pleurocystidia. Both species also
share basidiospore ornamentation characteristics (an incomplete reticulum with a slightly zebroid pattern) and a
hyphoepithelium pileipellis. Lactarius austrorostratus grows under Castanopsis whereas L. rostratus is associated with
Fagus in moss cushions. Another closely related species, L. rubrocorrugatus, is a small reddish brown species with
completely transparent latex. The other distinguishable character between L. austrorostratus and L. rubrocorrugatus
is the pleuromacrocystidia. L. austrorostratus has conspicuous protruding cystidia (up to 40 µm) with acute apex
whereas in L. rubrocorrugatus the cystidia are not protruding to slightly protruding up to 20 µm with a mucronate to
moniliform apex.
Lactarius chichuensis W.F. Chiu, Lloydia 8(1): 38, 1945 (Figure 4 and 11j).
Basidiocarps small to medium-sized. Pileus 5−37 mm diam., broadly convex to convex initially with umbo, becoming
infundibuliform with age; surface dry, smooth to wrinkled, color generally varying from brown (6E4−7E6) to reddish
brown (8D8, 9D−E8), with paler shade near margin, brownish orange (6C4−6) to light brown (6D7−8), in some
specimens brownish (7C7) to light brown (7D4−5) to grayish brown (7E3) to brown (7E4) with cream-colored margin,
sometimes with a fine whitish powder covering the surface; margin not striate, involute initially and becoming incurved
to straight in age. Lamellae subdecurrent to decurrent, crowded, 0.5−3 mm broad, grayish orange (5B4) to brownish
orange (5C4), light brown (7D4) to brown (7E4) when older, with 2−3 series of lamellulae. Stipe 8−24 × 2−6.5 mm,
cylindrical, central to eccentric; surface dry, smooth, light brown (7D6) to brown (6−7E6). Context 1−3 mm broad in
pileus, hollow in stipe, pale orange (5A3) to grayish orange (5B3−B4); odor strong, like L. quietus or Pentatomidae
bugs; taste mild. Latex abundant, watery white to white, unchanging on exposure, unchanging with 10 % KOH, pale
yellow on white tissue paper and unchanging on white cotton handkerchief. Macrochemical reaction on context: olive
brown (4D6) to light brown (5D6) with 10 % KOH, brown (6E7) with FeSO4.
Basidiospores globose to broadly ellipsoid, 6.1−6.7−7.3−8.1(−8.3) × 5.5−6.0−6.4−7.2(−7.3) µm; Q = 1.02−1.10
−1.16−1.28; ornamentation amyloid; ridges up to 1 µm high forming a zebroid ornamentation composed of parallel
irregular, short and long ridges, never reticulate; plage inamyloid. Basidia 50−57 × 13−18 µm, 4-spored, subclavate,
with fine granules. Pleuromacrocystidia rare to abundant, 45−71 × 10−15 µm, protruding up to 30 µm, subfusiform,
bent to straight with mucronate to moniliform apex, typically with refractive contents at apex. Pseudocystidia 3−6 µm
diam., slightly protruding, cylindrical, tortuous to straight, with fine granulate content. Lamellar edge heterogeneous,
consisting of basidia, marginal cells and cheilocystidia; marginal cells 12−28 × 7−15 µm, subcylindrical to clavate;
cheilocystidia abundant 31−45 × 10−19 µm, protruding up to 15 µm, subfusiform to subclavate, rarely clavate,
with refractive contents at apex. Lamellar trama consisting of globose cells, septate hyphae and lactiferous hyphae.
Pileipellis a hyphoepithelium, with a dense upper layer of repent hyphae and an underlying layer of globose cells,
suprapellis composed of cylindrical hyphae about 20−40 µm thick; subpellis consisting of globose cells about up to
20 µm diam.
Habitat: gregarious on ground in montane mixed forest with Fagaceae and Pinus kesiya.
Distribution: reported from China (Chiu 1945, Wang & Liu 2002), Thailand.

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FIGURE 4. L. chichuensis: a. basidiospore, b. cheilocystidia, c. basidia, d. pleuromacrocystidia, e. pseudocystidia, f. marginal cells, g.
pileipellis (a: KW271, b−g: KW421) (scale bar = 10 µm).
Collections examined: THAILAND, Chiang Rai province, Mae Fah Luang district, Doi Mae Salong Nok
sub-district, Doi Mae Salong, alt. 1269 m., N20º16.90 E99º62.30, 13/07/2012, KW352 (GENT!, MFLU!);−ibid.,
27/07/2012, KW372 (GENT!, MFLU!);−ibid., 08/08/2012, KW388 (GENT!, MFLU!);−ibid., 16/09/2012, KW403
(GENT!, MFLU!);−ibid., 28/08/2013, KW465 (GENT!, MFLU!);−ibid., 10/09/2013, KW467 (GENT!, MFLU!);
Chiang Mai province, Mae Teang district, Pa Pae sub-district, Bahn Pha Deng village, mushroom research center,
N19º17.12 E98º44.00, alt. 900 m, 13/05/2011, KW012 (GENT!, MFLU!); Chiang Mai province, Mae Teang district,

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Pa Pae sub-district, Bahn Pha Deng village,Pathummikaram Temple, forest trail, alt. 1050 m, 07/06/2012, KW271
(GENT!, MFLU!);−ibid., 07/06/2012, KW272 (GENT!, MFLU!).
Comments: Lactarius chichuensis is a distinctive species in the subgenus because of its zebroid basidiospore
ornamentation. The species has small, reddish brown basidiocarps and a strong L. quietus-like or Pentatomidae bug
odor. The species was discovered by Chiu (1945). The holotype is in poor condition and only the spore ornamentation
was studied by Chiu. Later the species was described in more detail and distinguished from a look-alike species,
L. hirtipes J.Z. Ying by Wang & Liu (2002) on account of its different basidiospore ornamentation. Morphological
characters of our specimens are consistent with the documentation of Wang & Liu (2002). In our collections we
sometimes observed the pileus to be whitish pruinose. Wang & Liu (2002) stated that the species is found in forests
with Fagaceae, whereas we found the species in mixed forest.
Lactarius fuscomaculatus Wisitrassameewong & Verbeken, sp. nov. (Figure 5 and 11b)
MycoBank number: MB811743; Facesoffungi number: FoF00636
Diagnosis: a medium sized species with a brown to orange-brown pileus and remarkably dark brown spots
or tinges, white latex, a strong odor of Pentatomidae bugs, incompletely reticulate basidiospore ornamentation,
pleuromacrocystidia rare and pileipellis a hyphoepithelium.
Etymology:—‘fuscomaculatus’ refers to the dark, brownish spots on the pileus.
Typus:—THAILAND, Chiang Rai province, Muang district, Thasai sub-district, forest near Doi Pui Reverse
Signal Station, Doi Pui, N19º49.26 E99º52.19, alt. 655 m, 31/07/2012, KW373 (holotype, GENT!, isotype, MFLU!).
Basidiocarps medium sized. Pileus 25−62 mm diam., broadly convex initially, turning slightly infundibuliform to
deeply infundibuliform in age, with a more or less distinct papilla; surface dry, more rugose in the center in age, brown
(7D8 to 7E7) to dark brown (8F7) in the center, towards the margin, paler, brownish orange (5C5) to brown (6D7) to
pale yellow (3A3), typically becoming uneven in color in age, with dark brown (8F7) discolorations, varying from
spotted to brushed over the whole surface except the margin; margin indistinctly striate, slightly crenulate. Lamellae
subdecurrent to decurrent, 1−3 mm broad, crowded, with 3−4 series of lamellulae, pale yellow (4A3) to cream-colored,
discoloring light brown (6D6) to brown (7E6), spotted in age. Stipe 34−76 x 4−7 mm, cylindrical, central, rarely slightly
eccentric; surface dry, smooth, whitish pruinose, particularly in young specimens, dull yellow (3B3) to olive brown
(4D6) at the apex, yellowish brown (5E4) to dark brown (7F5) towards the base, sometimes brownish orange (7C7),
with 1−2 mm long hairs at the base. Context 0.5−4 mm broad in the pileus, partially hollow to completely hollow in
stipe, pale yellow (3A3); odor strong, reminiscent of L. quietus or Pentatomidae bugs; taste mild. Latex watery white
to white, abundant, unchanging on exposure, unchanging with 10% KOH, unchanging on white tissue paper and on
white cotton handkerchief; taste slightly astringent and becoming faintly peppery. Macrochemical reaction no reaction
on the context with 10% KOH, or with FeSO4.
Basidiospores globose to broadly ellipsoid, 6.0−6.6−7.2−7.7(−7.8) × 5.5−6.1−6.6.−7.0(−7.2) µm, Q = 1.02−1.08
−1.10−1.21 (n=100); ornamentation amyloid, composed of irregular ridges up to 1 µm high, forming an incomplete
reticulum, warts and ridges connected by fine lines; isolated warts present; plage inamyloid to distally amyloid. Basidia
42−53 × 13−17 µm, 4-spored, some 2-spored, subclavate to clavate; with guttate contents. Pleuromacrocystidia rare,
protruding up to 10 µm, 55−68 × 13−17 µm, fusiform, with a mucronate, occasionally ramified apex. Pleuropseudocystidia
scarce to abundant, 3−6 µm diam., not emergent to slightly emergent, cylindrical to tortuous with an obtuse apex, often
broadened at the apex. Lamellar edge heterogeneous, composed of basidia, abundant cylindrical to subclavate, thin-
walled marginal cells 13−26 × 5−13 µm; cheilocystidia absent to rare, 34−38 ×11−14 µm, not emergent, fusiform with
a mucronate apex. Lamellar trama consisting of lactifers and sphaerocysts. Pileipellis a hyphoepithelium, with a thin
upper layer of repent or oblique hyphae; suprapellis composed of cylindrical hyphae, 10−20 µm thick; subpellis a layer
of large globose cells, up to 30 µm diam., mixed with cylindrical to inflated hyphae.
Habitat: gregarious to scattered on the ground in montane tropical forests with Fagaceae.
Collections examined: THAILAND, Chiang Rai province, Muang district, Thasai sub-district, forest near Doi
Pui Reverse Signal Station, Doi Pui, N19º49.26 E99º52.19, alt. 655 m, 31/07/2012, KW373 (holotype, GENT!,
isotype, MFLU!);−ibid., 25/07/2011, KW111 (GENT!, MFLU!);−ibid., 25/07/2011, KW112 (GENT!, MFLU!);−ibid.,
01/09/2011, KW126 (GENT!, MFLU!);−ibid., 01/09/2011, KW128 (GENT!, MFLU!);−ibid., 01/09/2011, KW129
(GENT!, MFLU!);−ibid., 25/07/2012, KW370 (GENT!, MFLU!); Chiang Rai province, Mae Fah Luang district, Doi
Mae Salong Nok sub-district, Doi Mae Salong, alt. 1269 m, N20°16.90 E99°62.30, 30/05/2012, KW221 (GENT!,
MFLU!);−ibid., 30/05/2012, KW223 (GENT!, MFLU!); Chiang Rai province, Mae Fah Luang district, Doi Mae Salong
Nok sub-district, Doi Mae Salong, N20º17.23 E99º61.69, alt. 1193 m, 22/07/2012, KW365 (GENT!, MFLU!);−ibid.,

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28/08/2013, KW466 (GENT!, MFLU!); Chiang Mai province, Mae-On district, Huaikaew sub-district, Bahn Pok M.1,
N18º53.08 E99º21.45, alt. 1040 m, 02/06/2012, KW236 (GENT!, MFLU!); Chiang Mai province, Mae-On district,
Huaikaew sub-district, Bahn Mae Kampong, N18º51.43 E99º22.09, alt. 1450 m, 03/06/2012, KW249 (GENT!,
MFLU!).
FIGURE 5. L. fuscomaculatus: a. basidiospore, b. cheilocystidia, c. marginal cell, d. basidia, e. pseudocystidia, f. pleuromacrocystidia, g.
pileipellis (a and c−f: KW365, b and g: KW373, holotype) (scale bar = 10 µm).

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Comments: Lactarius fuscomaculatus is widely distributed in tropical forests with Castanopsis and Quercus in
Northern Thailand. The species can be confused with a closely related species, L. rubrobrunneus due to similarities in
basidiocarps size, color, latex features and habitat. Both species are very similar in the immature stage, however, according
to our experience, brown spots on the pileus are often found in fully mature fruiting bodies of L. fuscomaculatus, while
L. rubrobrunneus is more unicolored. Under the microscope, both species have basidiospores with an incomplete
reticulum and not many cystidia. A slight difference was observed in their pileipellis structures; L. rubrobrunneus
has in part a very thin layer of repent hyphae which is like a transition between an epithelium and a hyphoepithelium,
whereas L. fuscomaculatus has a more complete layer of repent hyphae covering the pileus. Lactarius fuscomaculatus
may also be confused with L. tangerinus in the field. Lactarius tangerinus has smaller basidiomata, is typically paler
in color without dark brown spots and possesses transparent latex. For more details on the difference between these
two species, see under L. tangerinus.
FIGURE 6. L. inconspicuus: a. basidiospore, b. pseudocystidia, c. pleuromacrocystidia, d. cheilocystidia, e. basidia, f. marginal cell, g.
pileipellis (a−f: LTH256, g: KW339, hylotype) (scale bar = 10 µm).

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Lactarius inconspicuus H.T. Le & F. Hampe, sp. nov. (Figure 6 and 11d)
MycoBank number: MB811744; Facesoffungi number: FoF00637
Diagnosis: a small to medium sized species recognized by the brownish orange cap with paler margin, white
latex turning pale yellow on exposure and on white tissue paper and white handkerchief, with incomplete reticulate
basidiospore ornamentation, large and protruding pleuromacrocystidia and an ixotrichodermal pileipellis.
Etymology:—‘inconspicuus’ refers to the inconspicuous macromorphological characters of the species.
Typus:—THAILAND, Chiang Mai province, Doi Suthep-Pui national park, Sangasabhasri Lane to Huai Kok Ma
Village, N18º48.62 E98º54.60, alt. 1145 m, 05/07/2012, KW339 (holotype, GENT!, isotype, MFLU!).
Basidiocarps small to medium sized. Pileus 10−56 mm diam., convex-umbonate in immature specimens, becoming
plano-convex with depressed disc; surface minutely rugulose, dry to slightly sticky, glossy when moist, brown (7E6)
to dark brown (7F8) in center or at least on umbo, brown (6E−F6) to light brown (6D7) to brownish orange (6C−D6),
paler and cream-colored at margin; margin estriate when immature, becoming striate with age, crenulate. Lamellae
subdecurrent to decurrent, 1−3 mm broad, crowded, with 3−4 series of lamellulae, yellowish white (2A2), pale yellow
(4A3) to light yellow (4A4), turning brownish orange (6B−C7, 7C−D6) to reddish brown (8E5) when bruised. Stipe
20−75 × 2−8 mm, cylindrical to tapering upwards; surface dry to moist, smooth, brownish yellow (6B−C6) to brownish
orange (6C8−7C8) to brown (7E−F8), fistulose, whitish pruinose at base. Context 1−3 mm thick in pileus, pale cream
to orange-white (5A2) to brownish orange (5C−D6); odor faint, like L. quietus or Pentatomidae bugs; taste mild.
Latex abundant, watery white, slowly turning pale yellow on exposure, unchanging with 10 % KOH, pale yellow on
white tissue paper, pale yellow on white handkerchief; taste mild. Macrochemical reaction on the context: light brown
(5D4−D5) with 10 % KOH, grayish yellow (4B3) with FeSO4.
Basidiospores typically subglobose to broadly ellipsoid, rarely globose, 6.1−6.9−7.4−8.0(−8.1) ×
5.5−5.8−6.3−6.9(−7.0) µm; Q = 1.03−1.13−1.16−1.28 (n = 100); ornamentation amyloid, up to 1.3 µm high, consisting
of blunt to subacute thick ridges forming an incomplete to almost complete reticulum; isolated warts common; plage
inamyloid, sometimes slightly distally amyloid. Basidia 30−62 × 8−18 µm, mostly 4-spored, sometimes 2-spored,
subcylindrical to subclavate, with fine granules and guttate contents. Pleuromacrocystidia abundant, 30−114 × 8−20
µm, protruding up to 30 µm, subcylindrical to subfusiform, with mucronate to moniliform apex, with needle-like
contents and fine granules. Pleuropseudocystidia not protruding, 3−5 µm diam., tortuous to straight, cylindrical,
with fine granules. Lamellar edge heterogeneous, consisting of basidia, cylindrical to subclavate marginal cells
15−36 × 8−17 µm and abundant cheilocystidia 30−52 × 8−18 µm, not protruding to slightly protruding up to 10 µm,
subfusiform to fusiform, with mucronate to moniliform apex. Lamellar trama consisting of globose cells, septate
hyphae and lactiferous hyphae. Pileipellis an ixotrichoderm, 100−120 µm thick, consisting of erect cylindrical hyphae,
or sometimes, repent cylindrical hyphae.
Habitat: solitary to gregarious on soil in montane tropical forests, under Castanopsis armata.
Collections examined: THAILAND, Chiang Mai province, Doi Suthep-Pui national park, Sangasabhasri Lane
to Huai Kok Ma Village, N18º48.62 E98º54.60, alt. 1145 m, 02/06/2005, LTH256 (GENT!, CMU!, SFSU!);−ibid.,
30/05/2004, LTH098 (GENT!, CMU!, SFSU!);−ibid., 24/06/2005, LTH306 (GENT!, CMU!, SFSU!);−ibid.,
24/06/2005, LTH307 (GENT!, CMU!, SFSU!);−ibid., 21/04/2011, KW003 (GENT!, MFLU!);−ibid., 05/07/2012,
KW339 (holotype, GENT!, isotype, MFLU!); Chiang Mai province, Mae Taeng district, Bahn Mae Sae, 50 km marker
on highway 1095, N19º14.59 E98º39.45, alt. 962 m, 03/06/2011, KW016 (GENT!, MFLU!).
Comments: This species has the general features of the subgenus but lacks any striking distinguishing characters.
In the field this species is similar to L. tangerinus. A microscopic examination revealed that these species can be
distinguished by: (1) larger pleuromacrocystidia in L. inconspicuus; (2) presence of a narrow mucus layer in the
pileipellis in L. inconspicuous; and (3) higher basidiospore ornamentation in L. tangerinus.
Lactarius kesiyae Verbeken & K.D. Hyde sp. nov. (Figure 7, 11g and 11h)
MycoBank number: MB811745; Facesoffungi number: FoF00638
Diagnosis: a medium sized species with smooth cap and glossy surface, brownish gray to brownish orange cap with
grayish green tints, latex watery white turning yellow on a white handkerchief, incompletely reticulate basidiospores,
protruding pleuromacrocystidia, an ixotrichoderm and association with P. kesiya.
Etymology:—‘kesiyae’ refers to the ectomycorrhizal tree, P. kesiya.
Typus:—VIETNAM, Lam Dong province, Lac Duong district, Xa Lat, Lang Biang National park, alt. 1545 m,
N12º01.57 E108º25.58, 12/06/2011, KW032 (holotype, GENT!, isotype, MFLU!).

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FIGURE 7. L. kesiyae: a. basidiospore, b. basidia, c. marginal cell, d. pleuromacrocystidia, e. cheilocystidia, f. pseudocystidia, g. pileipellis
(a−g: KW353) (scale bar = 10 µm).
Basidiocarps medium-sized. Pileus 18−49 mm diam., at first convex to broadly convex, then becoming plano-
convex with a more depressed disc, finally infundibuliform; surface smooth and slightly glossy, slightly sticky when

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moist; color darkest in immature specimens, dark blond (5D4) when young, grayish yellow (3−4C4), brownish
gray (5C2), reddish blond (5C3−4) to brownish orange (5C5) when mature, in some collections with grayish green
(25B4−B6) tints, color paler in dry condition, pale orange (5A3) to pale grayish orange (5B3−4); margin, paler,
yellowish white (2A2), estriate when immature, later becoming striate and slightly crenulate with age. Lamellae
subdecurrent to decurrent, 1−3 mm broad, crowded, with 2 series of lamellulae, pale cream to cream, to grayish orange
(6B5) when bruised. Stipe 30−56 × 3−8 mm, cylindrical, centrally attached; apex becoming concolorous with lamellae,
darker when moist, brownish orange (5C5), pale orange when dry. Context 3−5 mm broad in pileus, whitish, hollow
in stipe; smell fruity; taste mild, a bit sweet after a while, then faintly acrid. Latex watery white, moderately abundant,
unchanging on exposure, unchanging with 10% KOH, unchanging on white tissue paper, soon turning yellow on a
white cotton handkerchief; taste mild to slightly astringent. Macrochemical reaction no reaction on the context with
10% KOH, but becoming brownish (5E7) to light brown (6D6) with FeSO4 after a while.
Basidiospores globose to broadly ellipsoid, 6.3−6.9−7.1−7.8(−7.9) × 5.7−6.1−6.3−6.8(−7.0) µm; Q = 1.02−1.10
−1.13−1.19 (n=60); ornamentation amyloid, up to 1.2 µm high, composed of irregular to crenulate ridges, obtuse,
forming an incomplete reticulum; isolated warts common; plage distally amyloid. Basidia 48−54 × 12−18 µm, 4-spored,
clavate, with fine granules and guttate contents. Pleuromacrocystidia abundant, 54−100 × 11−16 µm, protruding up
to 30 µm, irregular narrowly fusiform, slender, thin-walled, partially with granular and needle-like or guttate contents;
apex mucronate, occasionally ramified. Pleuropseudocystidia abundant, 4−6 µm diam., not protruding, cylindrical
to broadened at apex, tortuous. Lamellar edge heterogeneous, with basidia, cylindrical to subclavate, thin-walled
marginal cells 14−28 × 6−10 µm,; cheilocystidia scarce to fairly abundant, 37−58 × 10−14 µm, slightly protruding
up to 10 µm, narrowly fusiform, with mucronate apex, with granules. Lamellar trama consisting of abundant lactifers
and sphaerocysts. Pileipellis an ixocutis to ixotrichoderm, covered by a thin glutinous layer; upper layer 150−200 µm
thick, composed of repent to erect hyphae; subpellis composed of cylindrical and inflated hyphae with a few globose
cells.
Habitat: gregarious or scattered on ground, in coniferous forest with P. kesiya.
Collections examimed: VIETNAM, Lam Dong province, Lac Duong district, Xa Lat, Lang Biang National park,
alt. 1545 m, N12º01.57 E108º25.58 , 12/06/2011, KW032 (holotype, GENT!, isotype, MFLU!);−ibid., 12/06/2011,
KW033 (GENT!, MFLU!); −ibid., 12/06/2011, KW034 (GENT!, MFLU!);−ibid., 12/06/2011, KW035 (GENT!,
MFLU!);−ibid., 12/06/2011, KW036 (GENT!, MFLU!); THAILAND, Chiang Rai province, Mae Fah Luang district,
Doi Mae Salong Nok sub-district, Doi Mae Salong, N20º08.67 E99º40.17, alt. 1015 m, 15/05/2012, KW207 (GENT!,
MFLU!);−ibid., 19/05/2012, KW210 (GENT!, MFLU!),−ibid., 24/05/2012, KW219 (GENT!, MFLU!);−ibid.,
30/05/2012, KW224 (GENT!, MFLU!);−ibid., 13/07/2012, KW353 (GENT!, MFLU!);−ibid., 13/07/2012, AV12-022,
(GENT!, MFLU!); Mae Hong Son province, coniferous forest along highway 1095, near Huai Nam Dang national
park, alt. 1322 m, N19º16.07 E98º37.86, 08/07/2012, KW346 (GENT!, MFLU!); Lampang province, Muangparn
district, Chaesorn sub-district, forest along highway 1252, N18º55.43 E99º23.40, alt. 1420 m, 15/06/2013, KW427
(GENT!, MFLU!).
Comments: Lactarius kesiyae grows in coniferous forests dominated by P. kesiya. It can be recognized by its
sticky and glossy appearance in moist conditions, and its pale brownish gray to pale brownish orange color with
greenish or orange to even pinkish tints on the pileus. The latex is watery white and turns yellow on a white cotton
handkerchief. Microscopically, the pileipellis is an ixotrichoderm and the pleuromacrocystidia, which are up to 100 µm
long in length, protrude conspicuously from the hymenium.
Microscopically, the sticky pileus is reflected as an ixocutis and it is not a common character for this subgenus.
A sticky pileus occurs in a few temperate species such as L. decipiens, L. duplicatus, and L. badiosanguineus Kühner
& Romagn. and it seems to be less common in tropical Asia. There are two tropical Asian species recorded as having
a thin slime layer in the pileipellis stucture, L. austrotabidus Verbeken & E. Horak, with an ixocutis or ixotrichoderm
and L. inconspicuus with an ixotrichoderm. In the field L. kesiyae could be confused with representatives of L. subg.
Lactarius (syn. L. subg. Piperites (Fr.) Kauffman) on account of this surface feature which is one of the dominant
characters of that subgenus. However, the overall brownish orange colors of L. kesiyae suggest it is a member of subg.
Russularia.
Lactarius rubrobrunneus H.T. Le & Nuytinck, sp. nov. (Figure 8 and 11c)
MycoBank number: MB811746; Facesoffungi number: FoF00639
Diagnosis: a medium sized species with reddish brown cap, incompletely reticulate basidiospores,
pleuromacrocystidia rare, pileipellis an epithelium to hyphoepithelium.

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Etymology:—‘rubrobrunneus’ refers to the reddish brown color of the cap.
Typus:—THAILAND, Chiang Mai province, Mae-On district, Huaikaew sub-district, Bahn Mae Kampong,
N18º51.43 E99º22.09, alt. 1450 m, 15/07/2012, KW356 (AV12-044) (holotype, GENT!, isotype, MFLU!).
FIGURE 8. L. rubrobrunneus: a. basidiospore, b. marginal cell, c. pleuromacrocystidia, d. pseudocystidia, e. basidia, f. pileipellis (a−f:
AV12-044, holotype) (scale bar = 10 µm).
Basidiocarps medium sized. Pileus 15−80 mm diam., convex to widely depressed or infundibuliform, papillate;
surface dry, greasy, slightly rugulose, dark brown (8F5−6) in center, reddish orange (7A6−8) to light reddish brown to
yellow-brown (6C6−7) to brown (6D7) at the margin. Lamellae 1−4 mm broad, decurrent, crowded, with 3−4 series
of lamellulae, forked, cream to grayish orange (5B4−5), sometimes paler, discoloring with reddish brown spots in
age. Stipe 50−105 × 2−8 mm, cylindrical to tapering upwards, central, dry, smooth, whitish to pale cream pruinose at
apex, light brown (6D4) to brown (6E7) to dark brown (6F6), fistulose, hairy at base. Context 1−3 mm thick in pileus,
cream to brownish cream (5B4−5), odor strong, reminiscent of L. quietus or Pentatomidae bugs; taste mild. Latex
watery white to white, abundant, unchanging on exposure, unchanging on white tissue paper and on a white cotton
handkerchief and with 10 % KOH, taste mild. Macrochemical reaction no reaction on context with 10% KOH, or with
FeSO4.
Basidiospores subglobose to broadly ellipsoid, 6.1−6.6−6.9−7.4(−7.5) × 5.6−6.0−6.3−6.9(−7.0) µm, Q =
1.05−1.10−1.11−1.23 (n = 40); ornamentation amyloid, an incomplete reticulum up to 1 µm high,, consisting of blunt
and irregular ridges, connected by thinner ridges, isolated warts common; plage inamyloid to distally amyloid. Basidia
41−57 × 12−16 µm, 4-spored, some 2-spored, subclavate, with guttate contents. Pleuromacrocystidia rare, 38−50 ×

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10−14 µm, not protruding, with guttate contents. Pleuropseudocystidia abundant, slightly protruding, 3−7 µm diam.,
with fine granules, irregular to tortuous, sometimes with broadened apex. Lamellar edge heterogeneous, consisting of
basidia and marginal cells without cheilocystidia, marginal cells abundant, 15−36 × 5−12 µm, mostly cylindrical to
subcylindrical to subclavate. Lamellar trama a combination of globose cells, septate hyphae and lactiferous hyphae.
Pileipellis a transition between epithelium and hyphoepithelium, with or without a thin layer of about 5−10 µm thick,
repent hyphae, subpellis layer consisting of small to large, globose cells, up to 35 µm diam., layer about 70−100 µm
thick.
Habitat: gregarious in montane tropical forests with Fagaceae.
Collections examined: THAILAND, Chiang Mai province, Jomthong district, Bahn Luang sub-district, Doi
Inthanon National Park, junction of highway 1009 and road to Mae Cham, N19º31.58 E98º29.64, alt. 1703 m,
25/06/2004, LTH149 (GENT!, CMU!, SFSU!); Mae Hong Son province, Huai Nam Dang National Park, nature trail,
alt. 1538 m, N19º18.29 E98º35.88, 29/06/2005, LTH334 (GENT!, CMU!, SFSU!); Chiang Mai province, Mae-On
district, Huaikaew sub-district, Bahn Mae Kampong, N18º51.43 E99º22.09, alt. 1450 m, 15/07/2012, KW356 (AV12-
044) (holotype, GENT!, isotype, MFLU!).
Comments: Lactarius rubrobrunneus is recognized by its reddish brown to orange-brown cap with a darker brown
shade in the center. Lactarius rubrobrunneus differs from L. fuscomaculatus by the lack of dark brown spots on
cap. Compared to L. fuscomaculatus, all collections of L. rubrobrunneus have a thinner layer of terminal hyphae in
the pileipellis, which is a transition between an epithelium and a hyphoepithelium. In addition, we have observed
cheilocystidia in L. fuscomaculatus collections, while they are completely absent in L. rubrobrunneus.
Lactarius rubrocorrugatus Wisitrassameewong & Nuytinck, sp. nov. (Figure 9 and 11i)
MycoBank number: MB811747; Facesoffungi number: FoF00640
Diagnosis: A small to medium sized species, cap red to reddish brown with a rugulose surface, latex transparent,
basidiospore ornamentation consisting of low ridges forming an incomplete reticulum, pleuromacrocystidia present
and pileipellis a hyphoepithelium.
Etymology:—‘rubrocorrugatus’ refers to the red and wrinkled pileus.
Typus:—THAILAND, Chiang Rai province, Muang district, Thasai sub-district, forest at Doi Pui Reverse Signal
Station, Doi Pui, alt. 740 m, N19º49.00 E99º52.03, 31/07/2012, KW384 (holotype, GENT!, isotype, MFLU!).
Basidiocarps small to medium sized. Pileus 7−44 mm diam., plane to infundibuliform, papillate initially,
becoming depressed with or without a papilla; surface dry, smooth in immature specimens, later becoming wrinkled
in mature specimens, hygrophanous, red (9B7−8) to reddish brown (9D7−8−E8), typically with dark brown (7F5)
shade in center; margin not striate in young specimens, becoming slightly striate in age, incurved, crenulate. Lamellae
decurrent, 1−2 mm broad, very crowded, sometimes forked, with 1−3 series of lamellulae, yellowish white to light
yellow (4A4) to cream, turning brown (6E5−E6) when bruised; edge slightly crenulate to even. Stipe 11−42 × 2−8
mm, cylindrical, fistulose; surface dry, smooth to slightly wrinkled, brownish orange (7C7) to brown (7E7−E8),
turning dark brown (7F8) when older, whitish pruinose at base. Context 1−3 mm broad in pileus, pale yellow (4A3)
to cream, unchanging when cut; odor reminiscent of L. quietus or Pentatomidae bugs; taste mild, sometimes sweetish
and bitter. Latex transparent, unchanging on exposure, unchanging on tissue paper and on a white cotton handkerchief.
Macrochemical reaction on the context: unchanging or slowly turning pale yellow with 10 % KOH, grayish green
(26E6) with FeSO4.
Basidiospores globose to broadly ellipsoid, 5.8−6.4−7.0−7.9 × 5.2−5.8−6.3−6.9 µm; Q = 1.01−1.09−1.13−1.25
(n=120); ornamentation amyloid, composed of ridges up to 0.7 µm high, forming an incomplete reticulum; isolated
warts common, sometimes clustered; plage inamyloid to distally amyloid. Basidia 45−73 × 9−18 µm, mostly 4-spored,
sometimes 1-spored, subclavate to subcylindrical, with guttate contents. Pleuromacrocystidia 44−87 × 11−20 µm,
abundant, not protruding to protruding up to 20 µm, subfusiform, with a mucronate to moniliform apex, with granules
and guttate contents. Pleuropseudocystidia abundant, 3−6 µm diam., cylindrical, tortuous, with fine granules. Lamellar
edge heterogeneous, with basidia, marginal cells and cheilocystidia; marginal cells 24−40 × 8−15 µm, subcylindrical,
subclavate to clavate; cheilocystidia 25−51 × 7−13 µm, rare to abundant, subfusiform, bent or irregular, with a
mucronate to moniliform apex, with granular contents. Lamellar trama consisting of globose cells, septate hyphae
and lactiferous hyphae. Pileipellis a hyphoepithelium, with an upper layer of repent to oblique hyphae; suprapellis a
thin layer of repent hyphae about 10−25 µm thick; subpellis 40−60 µm thick, consisting of globose cells up to 30 µm
diam.

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FIGURE 9. L. rubrocorrugatus: a. basidiospore, b. basidia, marginal cell, d. pseudocystidia, e. pleuromacrocystidia, f. cheilocystidia, g.
pileipellis (a: KW384, holotype, b−g: KW294) (scale bar = 10 µm).
Habitat: gregarious on soil, in coniferous forest, dominated by P. kesiya and in tropical rain forests, dominated by
Shorea sp., Quercus sp. and Castanopsis sp.
Collections examined: VIETNAM, Dalat province, Xa Xuan Truong, at km 7, left side of the main road, alt.
1499 m, N11º54.94 E108º32.01, 13/06/2012, KW042 (GENT!, MFLU!);—ibid. 13/06/2012, KW043 (GENT!,

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MFLU!);−ibid. 13/06/2012, KW045 (GENT!, MFLU!); THAILAND, Chiang Mai province, Mae Taeng District, Pa
Pae sub-district, Bahn Pha Deng village, Pathummikaram Temple, forest trail, alt. 1050 m, N19º06.28’ E98º44.47,
9/06/2012, KW294 (GENT!, MFLU!); Chiang Rai province, Muang district, Thasai sub-district, forest at Doi Pui
Reverse Signal Station, Doi Pui, alt. 740 m, N19º49.00 E99º52.03, 31/07/2012, KW381 (GENT!, MFLU!);−ibid.
31/07/2012, KW384 (holotype, GENT!, isotype, MFLU!);−ibid., 08/07/2013, KW453 (GENT!, MFLU!); Chiang Rai
province, Chiang Khong district, forest near Bahn Nurnsomboon, alt. 450 m, N20º07.77 E100º26.40, 26/08/2011,
KW123 (GENT!, MFLU!), Chiang Mai province, Mae Taeng District, Bahn Thapa, 22 marker on highway 1095, alt.
750 m, N19º07.41 E98º45.57, 31/07/2014, EDC14-505 (GENT!, MFLU!); Loei province, Phu Ruea district, junction
from highway 203, alt. 1045 m, N17º28.09 E101º26.18, 27/06/2013, KW443 (GENT!, MFLU!).
Comments: Lactarius rubrocorrugatus can be easily distinguished from the other Southeast Asian species with
transparent latex because of its small size, and a hygrophanous and rugulose cap. The other species with transparent
latex described in the present work are L. aquosus and L. tangerinus. Lactarius aquosus differs from L. rubrocorrugatus
by the zonate, smooth cap and a cutis for a pileipellis. Lactarius tangerinus has a reddish orange cap and a trichoderm
pileipellis. Lactarius rubrocorrugatus is also similar to the European L. rostratus Heilmann-Clausen because of the
characters mentioned above. The major difference can be found in the macrocystidia. Lactarius rubrocorrugatus has
larger cystidia and the apex is not as acute as in L. rostratus. Lactarius rubrocorrugatus has been found in Vietnam
and Thailand. The putative host range of the species is broad. The Vietnamese specimens were found in coniferous
forest dominated by P. kesiya at higher altitude, around 1500 m above sea level, while the Thai specimens were found
in evergreen forests dominated by members of the Fagaceae at lower altitude (alt. between 700–1000 m).
Lactarius tangerinus H.T. Le & De Crop, sp. nov. (Figure 10, 11e and 11f)
MycoBank number: MB811748; Facesoffungi number: FoF00641
Diagnosis: a small to medium sized species with reddish brown to reddish orange cap and a paler margin, watery
latex, incompletely to almost completely reticulate basidiospores, pleuromacrocystidia present and pileipellis a
trichoderm.
Etymology:—‘tangerinus’ refers to the reddish orange color on cap.
Typus:—THAILAND, Chiang Mai province, Mae Teang district, Pa Pae sub-district, Bahn Pha Deng village,
mushroom research center, N19º17.12 E98º44.00, alt. 900 m, 28/07/2004, LTH 203 (holotype GENT!, isotype, CMU!,
isotype, SFSU!).
Basidiocarps small to medium sized. Pileus 8−36 mm diam., plane to slightly infundibuliform with a central
depression; surface rugulose, typically darker in center, reddish brown (8E8−F8) to dark brown (7F8), reddish blond
(6C6), to beige, paler towards the margin, orange-yellow (4A3−5), light yellow (4A5) at the margin; margin striate at
maturity. Lamellae 1.5−4 mm broad, decurrent with tooth, crowded, with 3−4 series of lamellulae, yellowish white
(4A1−2) to light yellow (4A4) to grayish orange (5B5). Stipe 10−36 × 2−6 mm, cylindrical to tapering downwards,
central to eccentric; surface dry, smooth, rugose when old, with paler color at apex, grayish orange (6B4) to pale
orange (5A3) at apex, brownish orange (6C4), light brown (6D4), light brown (7D7−8), whitish pruinose at the base
solid to hollow. Context 1−2 mm broad in the pileus, pale pinkish cream (5A3) to gray cream (5A−B3); odor like L.
quietus or Pentatomidae bugs; taste mild. Latex transparent, abundant, unchanging on exposure, unchanging with 10
% KOH; taste mild. Macrochemical reaction on context: becoming pale grayish green with 10 % KOH, light grayish
blue with FeSO4.
Basidiospores subglobose to broadly ellipsoid, (5.8−)6.1−6.6−7.2−7.9 × 5.4−6.1−6.3−7.0 (−7.2) µm; Q =
1.02−1.09−1.13−1.25 (n=40); ornamentation amyloid, up to 1.8 µm high, composed of blunt to subacute, thick
irregular ridges, forming an incomplete to almost complete reticulum; short ridges interconnected by fine lines; plage
inamyloid to slightly amyloid. Basidia 30−65 × 9−18 µm, 4-spored, mostly subclavate, rarely subcylindrical, with fine
granules and guttate contents. Pleuromacrocystidia not abundant, 35−77 × 10−18 µm, subcylindrical to subclavate,
with mucronate apex, protruding up to 10 µm. Pleuropseudocystidia 2−4 µm broad, not protruding, tortuous to straight,
cylindrical, with fine granules. Lamellar edge heterogeneous, consisting of basidia, subcylindrical to subclavate to
obovoid marginal cells 15−30 × 4−15 µm, and a few cheilocystidia 39−49 × 11−15 µm, not protruding, subclavate,
with mucronate apex. Lamellar trama composed of cylindrical hyphae, lactiferous hyphae and sphaerocysts. Pileipellis
a trichoderm, about 35−50 µm thick, consisting of erect cylindrical hyphae, subpellis mainly with small globose cells,
around 10−20 µm diam., intermixed with hyphae.
Habitat: solitary or gregarious on soil among leaf litter, near Lithocarpus thomsonii and L. elegon stands.

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FIGRUE 10. L. tangerinus: a. basidiospore, b. pleuromacrocystidia, c. cheilocystidia, d. marginal cell, e. basidia, f. pseudocystidia, g.
pileipellis (a−g: LTH203, holotype) (scale bar = 10 µm).
Collections examined: THAILAND, Chiang Mai province, Mae Teang district, Pa Pae sub-district, Bahn Pha
Deng village, mushroom research center, N19º17.12 E98º44.00, alt. 900 m, 28/07/2004, LTH 203 (holotype GENT!,
isotype, CMU!, isotype, SFSU!);—ibid., 13/08/2004, LTH217 (GENT!, CMU!, SFSU!);−ibid., 01/07/2011, KW091
(GENT!, MFLU!);—ibid., 28/07/2014, EDC14-475 (GENT!, MFLU!).
Comments: Immature basidiocarps of this species might be mistaken for L. fuscomaculatus or L. inconspicuus.
However, L. fuscomaculatus has watery white latex and develops dark brown spots on the cap in mature specimens.
The latex also separates L. tangerinus from L. inconspicuus. The latter species has watery white latex that slowly turns
yellowish white or pale yellow. For the microscopic differences between both species, see under L. inconspicuus.

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FIGURE 11. basidiocarps a. L. aquosus (KW231), b. L. fuscomaculatus (KW373), c. L. rubrobrunneus (AV12-044, photo by A. Verbeken),
d. L. inconspicuus (KW339, photo by F. Hampe), e–f. L. tangerinus (EDC14-475, photo by E. De Crop), g–h. L. kesiyae (g: KW032, h:
KW353), i. L. rubrocorrugatus (KW384), j. L. chichuensis (KW271).

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Identification key to the Southeast Asian Lactarius species
1. Basidiocarps rather small sized, an average size around 20 mm .................................................................................................... (2)
1. Basidiocarps medium sized .............................................................................................................................................................(5)
2. Pileus margin typically with triangle tufts ............................................................................................................... Lactarius gracilis
2. Pileus margin without tufts .............................................................................................................................................................. (3)
3. Basidiospores complete reticulum; pleuromacrocystidia absent; stipe mostly with whitish pruinose at base ....................................
......................................................................................................................................................................... Lactarius crenulatulus
3. Basidiospores incomplete reticulum; pleuromacrocystidia present; stipe mostly with strigose at base .........................................(4)
4. Pileus smaller dimension (5−7 mm diam.), with or without an inconspicuous papilla; pileipellis a cutis ......... Lactarius perparvus
4. Pileus larger dimension (5−40 mm diam.), with an acute papilla; pileipellis an epithelium ........................ Lactarius glabrigracilis
5. Distant lamellae; pileus with sulcate striations ............................................................................................................................... (6)
5. Crowded lamellae; pileus without sulcate striations .......................................................................................................................(9)
6. Pleuromacrocystidia present ............................................................................................................................................................ (7)
6. Pleuromacrocystidia absent .............................................................................................................................................................(8)
7. Pleuromacrocystidia strikingly protruding from the hymenium; basidiospores complete reticulum ........ Lactarius sublaccarioides
7. Pleuromacrocystidia not protruding from the hymenium; basidiospores incomplete reticulum .............................Lactarius stubbei
8. Pileus surface non-velutinous; stipe long (26−71 mm in length) and often very hispid .................................Lactarius laccarioides
8. Pileus surface minutely velutinous; stipe shorter (9−22 mm in length) and hairs only at the base ...................Lactarius pasohensis
9. Latex transparent, completely watery and unchanging on exposure ............................................................................................. (10)
9. Latex watery white to white ..........................................................................................................................................................(13)
10. Pileus inconspicuously zoned, reddish brown to brown, paler towards margin; lamellae discoloring brown or with brown spots;
pileipellis a cutis .......................................................................................................................................Lactarius aquosus sp. nov.
10. Pileus without zonation .................................................................................................................................................................(11)
11. Pileipellis a trichoderm .........................................................................................................................Lactarius tangerinus sp. nov.
11. Pileipellis a hyphoepithelium ........................................................................................................................................................ (12)
12. Pleuromacrocystidia with a rostrate apex, remarkably protruding up to 40 µm .......................... Lactarius austrorostratus sp. nov.
12. Pleuromacrocystidia different; basidiospores with low ornamentation (less than 1 µm high), an incomplete reticulum; pileus rugu-
lose .............................................................................................................................................. Lactarius rubrocorrugatus sp. nov.
13. Pileipellis covered with a thin slime layer ..................................................................................................................................... (14)
13. Pileipellis without a thin slime layer ............................................................................................................................................. (15)
14. Latex watery white, unchanging on exposure, turning yellow on a white handkerchief, associated with conifers (Pinus) ................
................................................................................................................................................................... Lactarius kesiyae sp. nov.
14. Latex watery white, slowly turning to pale yellow on exposure; growing with Castanopsis ...........Lactarius inconspicuus sp.nov.
15. Basidiospore ornamentation zebroid, ridges up to 1 µm high ...........................................................................Lactarius chichuensis
15. Basidiospore ornamentation incomplete reticulum, ridges up to 1 µm high ................................................................................. (16)
16. Pileipellis a hyphoepithelium; pileus reddish brown to orange-brown with distinct dark brown discolorations and spots ................
..................................................................................................................................................... Lactarius fuscomaculatus sp. nov.
16. Pileipellis a transition between hyphoepithelium and epithelium; pileus more unicolorous, reddish orange to reddish brown .........
...................................................................................................................................................... Lactarius rubrobrunneus sp. nov.
Discussion
This contribution is the third in a series of publications reporting the diversity of L. subg. Russularia in Southeast Asia.
According to the species concept stated in De Queiroz (2007), speciation occurs when a lineage acquires genotypic
divergence and different recognizable characters. Thus, species delimitation is ideally based on the concordance of
morphological characters and molecular evidence. Including the previous studies of Wisitrassameewong et al. (2014a,
2014b), we have described 15 new species of L. subg. Russularia from mycological expeditions in Thailand, Malaysia
and Vietnam. Most of them grow in broadleaf evergreen forests with members of the Fagaceae, except for the conifer
associated taxon, L. kesiyae. Relatively few distinct field characters could be defined and applied for all described species
because of subtle macro-morphological differences among species on this subcontinent. Lactarius fuscomaculatus
and L. rubrobrunneus seem to form one of the most complex groups. These two species can be easily confused in
the field and are also closely related in our phylogenetic analysis. Lactarius fuscomaculatus mainly differs from L.
rubrobrunneus by the dark brown spots on its pileus and the subtle difference in the terminal layer of the pileipellis.
Although most Southeast Asian taxa are superficially similar in their basidiocarp color and latex features, which could
lead to confusion in field identification, we consider none of the Southeast Asian species to be morphologically cryptic
(as described in the part of identification keys). All 15 described species are well-delimited using ITS sequence data
and the molecular evidence is consistent with their morphological differences. Distant gills, sulcate pileus striation
and sticky pileus surface can be used as field characters in some species. We notice that representatives with a sticky

LACTARIUS SUBGENUS RUSSULARIA IN SOUTH-EAST ASIA Phytotaxa 207 (3) © 2015 Magnolia Press • 239
surface seem to be rare, at least in this region. Considering the low variety in latex features, this character is not
particularly useful to differentiate among species. Basidiospore ornamentation, presence or absence of true cystidia
and pileipellis structure appear to be more reliable for species delimitation. From our experience, many representatives
possess basidiospores with an incomplete to almost complete reticulum while a complete reticulum, isolated warts and
zebroid ornamentation sometimes occur. The loss of true cystidia arose during a speciation event in several taxa. The
presence of a thin slime layer and presence or absence of terminal hyphal elements in the pileipellis are considered
important characters.
Our molecular analysis involves specimens from Asia, North America and Europe. So far all Southeast Asian
taxa are endemic to the subcontinent and no intercontinental conspecificity with temperate representatives has been
found (Figure 1). All new species are well-supported in our molecular phylogram and we found concordance between
field characters, microscopic characters and phylogenetic positions. The closest relative of L. austrorostratus is L.
chichuensis and the newly proposed species is sister to the clade that includes L. rostratus and L. rubrocorrugatus.
Lactarius rubrocorrugatus, L. kesiyae and L. tangerinus form distinct groups in the phylogram. Lactarius aquosus and
the European L. quietus split from the same ancestor. Although both species are phylogenetically related and have an
inconspicuous pileus zonation, other features are different. Lactarius quietus is easy to recognize due to its pinkish
buff cap and strong Pentatomidae bug odor (Heilmann-Clausen et al., 1998). Microscopically, L. aquosus has a cutis
and L. quietus has a trichopalisade as a pileipellis. Lactarius inconspicuus falls within a clade with L. decipiens. Both
species have similar characters, such as yellowing milk, large and acute pleurocystidia and a thin glutinous layer with
erect terminal hyphae in the pileipellis. Lactarius decipiens mainly differs from the Asian taxon by the pinkish fruiting
body, the odor of Pelargonium and reticulate basidiospore ornamentation.
Our results and recent studies suggest that the diversity of L. subg. Russularia in Southeast Asia is higher than we
previously thought. We emphasize that tropical rainforests in this continent comprise many ectomycorrhizal trees and a
large diversity of Lactarius species. However, many regions in this continent are undersampled. DNA sequence data of
several known Southeast Asian taxa are lacking. Further expeditions are necessary to explore undescribed indigenous
species in undersampled areas and to obtain more sample collections and molecular data of known Asian species.
Additional gene markers are necessary in order to better resolve the evolutionary relationship between species.
Acknowledgement
This research was funded by the joint doctorate program of the “Bijzonder Onderzoeksfonds Gent University” (BOF),
Gent University and NSF-PEET grant #DEB-0118776 to Desjardin. The expedition to Vietnam was sponsored by an
FWO grant to Nuytinck. Thanks are extended to the Thailand Research Fund grant (BRG 5580009) under the research
grant entitled “Taxonomy, Phylogeny and Biochemistry of Thai Basidiomycetes” for financial support. The authors
are grateful to the assistance from the colleagues at Mae Fah Luang University and Chiang Mai University (Thailand)
and Ghent University (Belgium).
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