Presence of the four-spined pygmy devil, Arulenus validispinus (Orthoptera: Tetrigidae), confirmed in Bukidnon region on the island of Mindanao, Philippines

Abstract

The four-spined pygmy devil (Arulenus validispinus Stål, 1877) is an endemic species to the Philippines. It was described more than 140 years ago from a single female specimen. Since its description, only a single new record was known, reported by Skejo from the Lanao region in 2017 and based on a specimen from eBay. Here, we record the species from the Bukidnon Mountains. We present measurements of a male and a female we collected, with the description of the species morphology and habitat. This species differs from its congeneric Mia’s pygmy devil (A. miae Skejo & Caballero, 2016) by the sharp dorsal and lateral spines.

Full text

Journal of orthoptera research 2020, 29(2)
Journal of Orthoptera Research 2020, 29(2): 133–136
Abstract
The four-spined pygmy devil (Arulenus validispinus Stål, 1877) is an
endemic species to the Philippines. It was described more than 140 years
ago from a single female specimen. Since its description, only a single
new record was known, reported by Skejo from the Lanao region in 2017
and based on a specimen from eBay. Here, we record the species from the
Bukidnon Mountains. We present measurements of a male and a female
we collected, with the description of the species morphology and habitat.
This species differs from its congeneric Mia’s pygmy devil (A. miae Skejo &
Caballero, 2016) by the sharp dorsal and lateral spines.
Keywords
Arulenus miae, habitat, morphology, Mt. Pantaron, taxonomy
Introduction
The Philippines is biogeographically one of the most diverse
countries due to its high number of islands (Mittermeier et al.
1998). Mindanao, a major island of the Philippines, is located
on the southern part of the archipelago. Recently, discoveries of
a new species and records of pygmy grasshoppers were made in
Mindanao (Skejo and Caballero 2016, Tan et al. 2019, Mohagan
et al. 2020). The Bukidnon is located in the central part of Mind-
anao and contains one of the most extensive mountain massifs
of the island—the Mt. Pantaron Range—which is a major part of
the central cordillera (Gronemeyer et al. 2014). The mountain re-
gion has a high biodiversity value (Coritico et al. 2018). A faunis-
tic inventory was recently conducted in the area, during which an
interesting species of pygmy grasshopper was collected, Arulenus
validispinus, which had not been recorded for more than a century.
The four-spined pygmy devil (A. validispinus Stål, 1877) is an
obscure species that was, until today, known only from the holo-
type female collected by Semper in the Philippines without speci-
fied locality (Stål 1877, Skejo and Caballero 2016, Skejo 2017)
and a female specimen on eBay from the Lanao region of the is-
land of Mindanao. The other species of the genus, Mia’s pygmy
devil (A. miae Skejo & Caballero, 2016), inhabits the area west of
A. validispinus’ distribution (Skejo 2017).
Our study presents, for the first time, measurements and habi-
tat of a male A. validispinus.
Materials and methods
Entry protocol and permits.—Compulsory permits, such as an ap-
proved Gratuitous Permit (GP) from the Department of Environ-
ment and Natural Resources in compliance with RA 9147 for the
collection of the specimens and Institutional Animal Care and
Use Committee (IACUC), were obtained.
Field sampling, collection of specimens, photography, and measure-
ments.—The study was conducted in the lower and upper mon-
tane forest of Mt. Pantaron, Sitio Miaray, Barangay Mandahican,
Cabanglasan (8°27’73.0”N, 125°36’54.6”E; 1004 m.a.s.l.; 03–14
February 2020) (Fig. 1). The combination of standard belt-tran-
sect and opportunistic and random sampling was implemented
in the study. The collection of specimens was conducted along an
established 2-km transect covering 10 m x 5 m on both sides.
Specimens of Arulenus validispinus were collected by handpick-
ing when encountered during the diurnal (07:00 h–15:00 h) and
nocturnal (17:00 h–22:00 h) period. They were then put in vials
filled with 95% ethyl-alcohol for preservation. Specimens were
air-dried and mounted. Images of A. validispinus were taken using
a DSLR Canon EOS 700D camera combined with an AmScope
stereomicroscope. Final images of the species were edited using
licensed Adobe Photoshop CS software. An ocular micrometer
was used to measure the specimens. The standard methodology
of Skejo and Bertner (2017), Tumbrinck and Skejo (2017), and
Muhammad et al. (2018) were used for gathering measurements.
The following measurements were taken: Body length (from
fastigium to the end of pronotum), pronotum length (PL) (from
Presence of the four-spined pygmy devil, Arulenus validispinus (Orthoptera:
Tetrigidae), confirmed in Bukidnon region on the island of Mindanao, Philippines
AlmA B. mohAgAn1,2, Romeo R. PAtAno JR.1,2, mescel s. AcolA1,2, DAniel o. AmPeR1,2, Fulgent P. coRitico1,2,
VictoR B. AmoRoso1,2
1 Center for Biodiversity Research and Extension in Mindanao, Central Mindanao University, Musuan, Maramag, Bukidnon 8710, Philippines.
2 Department of Biology, College of Arts and Sciences, Central Mindanao University, Musuan, Maramag, Bukidnon 8710, Philippines.
Corresponding author: Romeo R. Patano Jr. (romeonojrpatano@gmail.com)
Academic editor: Ming Kai Tan | Received 28 April 2020 | Accepted 22 May 2020 | Published 30 November 2020
http://zoobank.org/7A320A66-20CE-4114-821C-F880EF11BAF5
Citation: Mohagan AB, Patano Jr RR, Acola MS, Amper DO, Coritico FP, Amoroso VB (2020) Presence of the four-spined pygmy devil, Arulenus
validispinus (Orthoptera: Tetrigidae), confirmed in Bukidnon region on the island of Mindanao, Philippines. Journal of Orthoptera Research 29(2):
133–136. https://doi.org/10.3897/jor.29.53718
Short Communication

Journal of orthoptera research 2020, 29(2)
A.B. MOHAGAN, R.R. PATANO JR., M.S. ACOLA, D.O. AMPER, F.P. CORITICO AND V.B. AMOROSO
134
the anterior margin to the caudal apex of the pronotum), pronotum
lobe width (PW) (between the lateral lobes), pronotum height
(PH) (lateral view from the bottom of the paranota to the tip of the
highest spine), fore femur length (FFL) (in lateral view, its greatest
length from the tip of the dorso–basal lobe to the tip of the knee),
fore femur width (FFW) (in lateral view, its greatest width), mid
femur length (MFL) (in lateral view, its greatest length from the tip
of the dorso–basal lobe to the tip of the knee), mid femur width
(MFW) (in lateral view, its greatest width), hind femur length
(HFL) (in lateral view, its greatest length from the tip of the dorso-
basal lobe to the tip of the knee), hind femur width (HFW) (in
lateral view, its greatest width), vertex width (VW) (between the su-
praocular lobes in dorsal views or between the eyes in frontal view),
compound eye width (CEW) (dorsal or frontal view), and antennal
length (AL) (from scapus to the tip of the last segment). The speci-
mens collected and examined in this study were deposited in Cen-
tral Mindanao University, University Museum, Zoological Section,
Tetrigidae collection. All measurements are shown in millimeters.
Diagnosis of the species.—We collected two specimens, a male and a
female, from Bukidnon. Our specimens are very similar to Stål’s type
specimen, which is from an unknown locality, as well as to the spec-
imens reported by Skejo (2017) in his diploma thesis, which came
from Lanao, 105.41 km from Bukidnon. The specimens of four-
spined pygmy devils are dark in coloration, and as in A. miae, have
reddish markings. Dorsum of pronotum bears four long spines: a
pair between the shoulders on the bulky elevation of the discus and
a pair in the metazona. Our specimens have slightly larger spines
and longer ventrolateral projections (Fig. 2) than the holotype (see
holotype of A. validispinus in Orthoptera Species File, Cigliano et al.
2020). The holotype has a third pair of wart-like spines located at
the anterior apex that are not observed in our specimens.
Comparison with congeners.—The genus Arulenus is endemic to the
Philippines with only two known species, A. miae and A. validis-
pinus. A. validispinus is similar to A. miae Skejo & Caballero, 2016,
and can be distinguished by the set of the following characters: (i)
prozona of pronotum granulated, very wrinkly (slightly granulate,
more or less smooth in A. miae), (ii) metazona of pronotum from
2.8/10 to 4.5/10 of pronotum length, bearing the first pair of spines
higher than the second (more than 2×), from 5.1/10 to 6.5/10 of the
length bearing the second pair of spines high, hind femora more
robust (length/maximal width ratio 2.4 in male and 2.5 in female),
and with dorsal margin undulate and tuberculate, and (iii) notable
spiky ventrolateral projections of the lateral lobes (paranota).
Material examined.—PHILIPPINES • (2/2) 1♂1♀. Bukidnon,
Cabanglasan, Barangay Mandahican, Sitio Miaray, Mt Pantaron,
8°27’73.0”N, 125°36’54.6”E, 1,004 masl, 03–14 Feb. 2020, AM-
011, A.B. Mohagan, R.R. Patano Jr., M.S. Acola, D.O. Amper, F.P.
Coritico, and V.B. Amoroso, Central Mindanao University, Univer-
sity Museum, Zoological Section.
Type locality.—The Philippines, no specified locality of the holo-
type label. Type series: a single female holotype, labeled Ins.
Philipp., originates from Semper’s collection and is deposited in
the entomological collections of the Naturhistoriska Riksmuseet
in Stockholm, Sweden.
Distribution.—Inhabiting tropical mountainous rainforests on
Mindanao (the Philippines) at 800–1,100 m above sea level:
known from Lanao and Bukidnon Region (present study).
Measurements.—Male (N=1). BL 11.1; PL 10.4; PW 6.2; PH 5.0;
FFL 4.0; FFW 0.8; MFL 4.5; MFW 0.6; HFL 6.1; HFW 2.5; VW 1.2;
CEW 1.0; AL 7.2.
Female (N=1). BL 12.0; PL 10.8; PW (between the tips of the
spines) 6.5; PH 5.2; FFL 4.15; FFW 0.14; MFL 4.6; MFW 0.65; HFL
6.52; HFW 2.65; VW 1.24; CEW 1.1; AL 7.6.
Habitat and ecology.—The species is found on tree bark in the mon-
tane forest (Fig. 3), similar to the habitat of A. miae and Spartolus pu-
gionatus Stål, 1877 (Mohagan et al. 2020). The associated vegetation
consists of the following species of trees: Shorea spp., Lithocarpus spp.,
Ficus spp., Pinanga spp.; and ferns: Sphaeropteris elemeri, S. polypoda, Al-
sophila fuliginosa, Taenitis blechnoides, Schizaea dichotoma and Selaginella
spp. Besides the Lanao region (Skejo 2017), here we report the species
from the Bukidnon region, more specifically Mt. Pantaron, Sitio Miar-
ay, Barangay Mandahican, Cabanglasan. These records finally confirm
that A. validispinus inhabits Mindanao island in the Philippines—an
answer to a 140-year old question of this species’ distribution.
Fig. 1. Map of A. the Philippines and B. Mindanao showing the
known distribution of A. validispinus in C. Mt. Pantaron, Sitio Mi-
aray, Barangay Mandahican, Cabanglasan where the specimens
were collected (red circles) and in Lanao region based on a speci-
men from eBay (blue triangle).
Results and discussion
Diagnosis of the genus.—The genus can be easily distinguished from
similar genera by the following characters: a single paranotal lobe
present, tegmina and alae absent, lateral paranotal lobes turned
outwards, pronotum surface smooth, slightly wrinkled, and high
spines present on pronotal discus. The genus can be separated
from Discotettix by the shape of paranota, absence of wings, pro-
notum that is not wrinkled and not tuberculated, and smooth
femora surface (Skejo 2017).

A.B. MOHAGAN, R.R. PATANO JR., M.S. ACOLA, D.O. AMPER, F.P. CORITICO AND V.B. AMOROSO 135
Journal of orthoptera research 2020, 29(2)
Fig. 2. Habitus of the four-spined pygmy devil, Arulenus validispinus Stål, 1877, a male from Bukidnon (Mt. Pantaron) in A. dorsal and
B. lateral view.
Fig. 3. Habitat of the four-spined pygmy devil, Arulenus validispinus Stål, 1877, in A. lower and B. upper lowland dipterocarp rainforest
of Mt. Pantaron (about 1,004 masl).

Journal of orthoptera research 2020, 29(2)
A.B. MOHAGAN, R.R. PATANO JR., M.S. ACOLA, D.O. AMPER, F.P. CORITICO AND V.B. AMOROSO
136
Acknowledgements
The authors would like to thank the Department of Science
and Technology Grants-in-Aid (DOST-GIA) program entitled “Bi-
odiversity in Selected Mountain Ecosystems of Mindanao for Con-
servation and Sustainable Development” as the funding agency,
the Philippine Council for Agriculture, Aquatic and Natural Re-
sources Research and Development for monitoring the research,
and the Department of Environment and Natural Resources Re-
gion 10 for the issuance of Gratuitous Permit (GP). The authors
would like also to acknowledge Central Mindanao University ad-
ministration and the leadership of Dr. Jesus Antonio G. Derije,
University President, for his valuable help in implementing and
supporting the research. Thanks to Josip Skejo for confirming the
species ID and for proofreading the manuscript.
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Supplementary material 1
Authors: Alma B. Mohagan, Romeo R. Patano Jr., Mescel A. Acola,
Daniel O. Amper, Fulgent P. Coritico and Victor B. Amoroso
Data type: Morphometric data
Explanation note: We provide supplementary data on Arulenus
validispinus morphometric data and comparing to its sibling
Arulenus miae.
Copyright notice: This dataset is made available under the Open
Database License (http://opendatacommons.org/licenses/
odbl/1.0/). The Open Database License (ODbL) is a license
agreement intended to allow users to freely share, modify,
and use this Dataset while maintaining this same freedom
for others, provided that the original source and author(s)
are credited.
Link: https://doi.org/10.3897/jor.29.53718.suppl1