New Distribution Record for Paraspartolus curiosus Gunther, 1939 (Orthoptera: Tetrigidae) with Notes on Taxonomy and Biogeography

Abstract

Paraspartolus Günther, 1939 is a monotypic genus endemic to the Philippines. Its only species-P. curiosus Günther, 1939-has been known only from Cape Engaño, Santa Ana, Cagayan, Luzon Island. Even though the species was described more than 80 years ago, only three specimens have been known, and nothing about the species' coloration, variability, or ecology was noted. In this study, we provide live photographs of the species for the first time from Negros Island-some 1000 km away from the type locality. We present detailed measurements of the collected male and female specimens and describe the species' color variations and microhabitats, including their bryophyte associates. We provide comments on the distribution of the species and identify problems with the higher classification.

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*Corresponding author: romeonojrpatano@gmail.com
RESEARCH NOTE
New Distribution Record for Paraspartolus curiosus
Gunther, 1939 (Orthoptera: Tetrigidae) with Notes
on Taxonomy and Biogeography
Romeo R. Patano Jr.1*, Niko Kasalo3, Victor B. Amoroso1,2, Maria Melanie M. Guiang1,2,
Fulgent P. Coritico1,2 and Alma B. Mohagan1,2
1Institute of Biological Sciences, College of Arts and Sciences,
2Center for Biodiversity Research and Extension in Mindanao,
Central Mindanao University, Musuan, Maramag, Bukidnon 8710 Philippines
3Matice Hrvatske 11, 80101 Livno, Bosnia and Herzegovina
Paraspartolus Günther, 1939 is a monotypic genus endemic to the Philippines. Its only species – P.
curiosus Günther, 1939 – has been known only from Cape Engaño, Santa Ana, Cagayan, Luzon
Island. Even though the species was described more than 80 years ago, only three specimens have
been known, and nothing about the species’ coloration, variability, or ecology was noted. In this
study, we provide live photographs of the species for the first time from Negros Island – some
1000 km away from the type locality. We present detailed measurements of the collected male
and female specimens and describe the species’ color variations and microhabitats, including
their bryophyte associates. We provide comments on the distribution of the species and identify
problems with the higher classification.
Keywords: Balinsasayao Twin Lakes Natural Park, biogeography, microhabitat, montane forest,
Ophiotettigini, taxonomy
The Philippine archipelago is a known habitat of diverse
fauna, including some interesting pygmy grasshoppers
of the orthopteran family Tetrigidae. Recent research has
been focused on the Mindanao Islands, and discoveries of
new species and records of pygmy grasshoppers followed
(Skejo and Caballero 2016; Tan et al. 2019; Mohagan et
al. 2020a, b, c; Patano et al. 2021a, b). On the other hand,
many islands in the Philippines are still underexplored
such as the Visayas Islands, which are known habitats of
pygmy grasshoppers. This study focuses on the Negros
region, home to some island endemic tetrigids (Hebard
1923; Cigliano et al. 2017). One of the important
protected forest and mountainous areas in Negros Island
is the Balinsasayao Twin Lakes Natural Park (BTLNP)
– a declared protected area due to its many endemic and
threatened species of flora and fauna (Dolino et al. 2004;
Aureo et al. 2019, 2021). BTLNP is one of the Philippines'
long-term ecological research sites (LTERs).
Paraspartolus curiosus Günther, 1939 is the only known
species of its genus, which was only recently assigned
to the tribe Ophiotettigini Tumbrinck & Skejo, 2017,
subfamily Metrodorinae Bolívar, 1887. The higher
taxonomic placement is still unclear, owing to the many
problems of Tetrigidae classification (Pavon-Gozalo et
al. 2012; Tumbrinck and Skejo 2017). P. curiosus is a
fittingly named curious and rarely observed species. It
was originally described over 80 years ago (Günther
1939) from Luzon in the far north of the Philippines.
Until now, the holotype female and the two paratypes
(male and female) deposited in London, United Kingdom
(Cigliano et al. 2017) were the only known records
Philippine Journal of Science
152 (6B): 2463-2468, December 2023
ISSN 0031 - 7683
Date Received: 23 Mar 2023

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of this species. The male is in bad condition, lacking
legs and a head, whereas the females are, apart from
antennae, mostly intact (Natural History Museum 2023).
The color has faded in all three specimens. For the first
time, our recent faunistic survey in a forested area of
Negros Island in BTLNP (an LTER site), Sibulan, Negros
Oriental, documented the species in its natural habitat,
specifically on its host plant. Moreover, we provide the
new distribution record, habitat description, and potential
threats of the species in Negros Island, Philippines.
In the present study, we present new records of two more
specimens (male and female) more than 1000 kilometers
from the type locality and provide live photographs
showing the colorations of the species that cannot be
easily observed in old museum collections. We assess
the differences between the male and female specimens,
provide descriptions of microhabitats, and identify
potential threats. Lastly, we provide taxonomic and
biogeographic comments.
Prior to the fieldwork in BTLNP, Sibulan, Negros Oriental,
the research plan was initially presented to the leader and
members of the people’s organization and the Department
of Environment and Natural Resources (DENR). The latter
approved and issued the Gratuitous Permit, in compliance
with Republic Act No. 9147, to collect the specimens.
The present study was conducted in the locality of Negros
Oriental, Sibulan – specifically in the forested areas
of BTLNP (09°21.586” N, 123°10.892” E, 905 masl,
28–29 Sep 2023), which is one of the known LTERs of
the Philippines (Figure 1). Opportunistic and random
sampling methods were implemented in the established
2-ha permanent plot in the area. Specimens were collected
along the established transects in the protected area.
Specimens of P. curiosus were photographed in their
natural habitat and then collected through handpicking
during the diurnal period (07:00–15:00 h). Specimens
were preserved in vials with absolute ethyl alcohol for
future molecular study. Male and female specimens were
photographed using the Olympus TG6 digital camera.
Images were edited using licensed Adobe Photoshop
CS software. A digital caliper was used to measure the
specimens employing the standard methodology of Skejo
and Bertner (2017), Tumbrinck and Skejo (2017), and
Muhammad et al. (2018). The specimens were identified
by comparison with the type specimens available on the
OSF (Cigliano et al. 2017) and the specimens from the
Figure 1. Distribution records of Paraspartolus curiosus Günther, 1939 in the Philippines in red dots (A) with a new island
record in Negros Island (B) specifically in Balinsasayao Twin Lakes Natural Park, Sibulan, Negros Oriental
(09°21.586” N, 123°10.892” E; 905 m asl).
Philippine Journal of Science
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National History Museum, London (Natural History
Museum 2023) and Museo Nacional de Ciencias
Naturales, Madrid (MNCN). The original description was
verified using the description by Günther (1939).
The measurements that were taken are the following:
body length (BL), pronotum length (PL), pronotum lobe
width (PLW), pronotum height (PH), fore femur length
(FFL), fore femur width (FFW), mid femur length (MFL),
mid femur width (MFW), hind femur length (HFL), hind
femur width (HFW), vertex width (VW), compound eye
width (CEW), and antennal length (AL). The specimens
were mounted, deposited, and displayed in the Central
Mindanao University, University Museum, Zoological
Section, Tetrigidae collection. All measurements are
shown in millimeters.
The monotypic genus Paraspartolus is most similar to
Spartolus, with which it shares the moderately elongated
head without a noticeable protrusion of the vertex but is
clearly separated from it by the following characteristics:
[i] short pronotum (apex reaching half of femur length);
[ii] lateral lobes contiguous with body, lacking sharp
projections; [iii] thicker anterior and middle femora; and
[iv] greyish to brownish color with yellow streaks and
patches (Figure 2).
The genus Paraspartolus belongs to the tribe Ophiotettigini
– together with Ophiotettx Walker, 1871, Rhopalotettix
Hancock, 1910, Spartolus Stål, 1877, and Uvarovithyrsus
Storozhenko, 2016. The elongated head shape has been
suggested as a clear synapomorphy of this supposedly
monophyletic (or holophyletic) tribe (Tumbrinck and
Skejo 2017), and there is no reason to doubt this at the
moment. The morphology of P. curiosus, most notably
the head morphology, strongly resembles that of many
other species attributed to this tribe, making it likely
monophyletic. The genus Rhopalotettix has been noted
to contain some species that strongly differ from the type
species (Tumbrinck and Skejo 2017). Rhopalotettix is
extremely important to consider since it contains species
with different combinations of elongation of the head and
the elongation of the vertex, which makes them important
in elucidating the evolution of these characters, but only
after appropriate revisions have been conducted.
Ophiotettigini is a morphologically very distinct tribe,
making it difficult to compare in depth to others. However,
the tribe Clinophaestini Storozhenko, 2013 shares with
Ophiotettigini some potential synapomorphies – namely,
the positioning of facial features and the way the vertex
forms a rostrum in Clinophaestini and Uvarovithyrsus.
An in-depth study is necessary to determine whether
Uvarovithyrsus and potentially Rhopalotettix belong to
Clinophaestini instead of Ophiotettigini, as indicated by
their similarly-shaped rostrums, or whether these tribes
are synonymous.
The placement of Ophiotettigini in the subfamily
Metrodorinae is a better reflection of its unique morphology
in the region than its true place in the Tetrigidae tree of
life. A proper definition of core Metrodorinae is still
lacking because even the type genus Metrodora Bolívar,
1887 includes many different morphologies (Pavon-
Gozalo et al. 2012; Kasalo et al. 2023). A comparison
Figure 2. Appearance of the Paraspartolus curiosus Günther,
1939 showing its color patterns (A–D) and frontal views
(E–F). Female (A–B) and male (C–D) specimens from
Balinsasayao Twin Lakes Natural Park, Sibulan, Negros
Oriental. Lateral (A and C) and dorsal (B and D) view.
Figure 3. The female specimen of Paraspartolus curiosus from
Ignacio Bolívar’s collection, reported by Paris (1993) as
“Cisthrecus ophthalmicus” (undescribed species). Photo:
Josip Skejo and M.N.C.N. Madrid.
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between Metrodorini and Ophiotettigini is not enough to
hypothesize how the two might be related. An extensive
review of SE Asian and American Tetrigidae, followed by
molecular phylogenies, will be necessary.
PHILIPPINES • (2/2) 1♂1♀. Negros Oriental, Sibulan,
BTLNP, 09°21.586” N, 123°10.892” E, 905 masl, 28–29 Sep
2023, R.R. Patano Jr. and V.B. Amoroso, Central Mindanao
University, University Museum, Zoological Section.
In a catalog of Ignacio Bolívar’s collection of Tetrigidae,
a male specimen of “Cisthrecus ophthalmicus” from
Mt. Makiling, Luzon, collected in 1937 by Baker is
mentioned (Paris 1993). This specimen was identified
as Paraspartolus curiosus by Josip Skejo in 2016. Upon
examining this specimen, we found it to be a female of
Paraspartolus curiosus, as it corresponds exactly to the
morphology of the other known specimens of this species.
Furthermore, the species “Cisthrecus ophthalmicus”
was never formally described, as indicated by the label
“especie no publicada”.
Luzon, Cape Engaño, Santa Ana, Cagayan; a female
holotype plus two male and female paratypes are deposited
in the entomological collections of the British Museum
of Natural History, National History Museum. Cape
Engaño is known to have forest patches and grasslands
over karst substrates, but there is no information on the
exact microlocality where the species was collected. It
is, thus, impossible to compare the type locality with the
new one until more specimens are found in Cape Engaño.
Known from northern Luzon (type locality, Cape Engaño),
southwestern Luzon (Mt. Makiling) (Paris 1993), and the
newly identified locality: tropical lower mountainous
rainforests on Negros, Visayas (the Philippines) at 900–
950 m above sea level – known from BTLNP, Sibulan,
Negros Oriental.
The three localities on the two islands are far apart from
each other, but there are no apparent differences that would
suggest that these populations represent separate species.
The Philippine archipelago formed during the last 30 My
(Mitchell et al. 1986), leaving a large window during
which the populations might have become separated.
Since this species and its close relatives are all flightless,
active migration does not seem likely. There may be
undiscovered populations between the known three, i.e.
P. curiosus might be a widely distributed species, which
could mean that there is a persistent gene flow between
them. Alternatively, it is possible that these populations are
separate but morphologically cryptic species, i.e. the genus
Paraspartolus is represented by many microendemic
species. It will be necessary to collect specimens from
the type locality and conduct molecular analysis to show
how different these populations really are.
Female (N = 1). BL 9.2; PL 4.8; PLW 2.8; PH 2.2; FFL
2.3; FFW 0.4; MFL 2.4; MFW 0.6; HFL 5.0; HFW 1.6;
VW 0.3; CEW 0.8; AL 3.9. Male (N = 1). BL 9.0; PL 4.5;
PLW 2.6; PH 2.1; FFL 2.2; FFW 0.2; MFL 2.4; MFW 0.4;
HFL 1.6; HFW 1.6; VW 0.3; CEW 0.7; AL 3.8.
The specimens of the three populations are morphologically
quite uniform, with no major differences observed in the
commonly used characters. Some sex-specific differences
have been observed: [i] the male specimen has more
yellowish colorations on its pronotum than the female,
and [ii] the pronotal apex of the male forms a more acute
angle than the female.
Female and male specimens of Paraspartolus curiosus
Günther, 1939 were observed in Balinsasayao Twin Lakes,
Sibulan, Negros Island perching on rotten logs and tree
bark (Ficus sp.), which are covered with bryophytes
(Pyrrhobryum spiniforme (Hedw.) Mitt. and some other
species from family Hypnaceae) (Figure 4).
These bryophytes might be a food source for the
species. This pristine habitat of Paraspartolus curiosus
Günther, 1939 is a typical lower montane old-growth
forest dominated by some trees (Ficus spp., Antidesma
Figure 4. Live female and male of Paraspartolus curiosus Günther,
1939, in dorsal and lateral views (A, C, and E) with their
respective microhabitats (B, D, and F).
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spp., and Euonymus spp.), some ferns (Alsophila spp.),
pandans (Freycinetia spp.), aroids (Alocasia spp.), and
pipers (Figure 5). The substrate is mostly covered with
big rocks with bryophytes. This locality was a declared
protected area in the year 2000 under Senate Bill No. 1067.
However, there are isolated cases of hardwood cutting
and poaching, which must be eradicated completely. This
record confirms that a population of P. curiosus inhabits
this area, as well as Luzon. The species is still only rarely
observed, and there is a possibility that this population
represents a separate evolutionary line, making this area
an important one for future studies, which is only possible
with continued and effective protection.
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Figure 5. Habitat of Paraspartolus curiosus Günther, 1939 in the
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ACKNOWLEDGMENTS
This research would not be possible without the support
of the DENR; the Balinsasayao Twin Lakes Farmers
Association Incorporated of Sibulan, Negros Oriental; and
CHED (Commission on Higher Education) for funding
the research project titled "Biodiversity Conservation
and Utilization for Product Development (BioConUP) in
Long-Term Ecological Research (LTER) Sites in Southern
Philippines." The authors also acknowledge Dr. Rolito G.
Eballe, President of Central Mindanao University, for his
unwavering support. We are grateful to Josip Skejo and
M.N.C.N. Madrid for making the Mt. Makiling specimen
available for our research.
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