Araneibatrus phuphaphet Yin & Jantarit, 2019

Yin, Zi-Wei & Jantarit, Sopark, 2019, Araneibatrus phuphaphet sp. nov., a new cavernicolous Pselaphinae from Satun Geopark, southern Thailand (Coleoptera: Staphylinidae: Pselaphinae), Zootaxa 4691 (1), pp. 83-87 : 84-85

Araneibatrus phuphaphet Yin & Jantarit , sp. nov.

( Figs 1–3 )

Type material. Holotype: THAILAND: ♂: ‘THAILAND: Satun Prov., Manang Dist., Phu Pha Phet Cave (sample # THA_SJ_STN10), Khao Banthat Wildlife Sanctuary , 99.9970° E, 7.1264° N (entrance of the cave), ground floor of deep area, 8.ii.2019, Jantarit, S. Nilsai, A. and Jantapaso, K. leg. ( NHM-PSU) ’ Paratypes (24 exx.): THAI- LAND: 6 ♂♂, 4 ♀♀: same collecting data as for holotype ; 2 ♂♂, 4 ♀♀: same location, except ‘ 31.v.2019, Jantarit, S. Surakhamhaeng, K. and Jantapaso, K. leg. ’; 3 ♂♂, 5 ♀♀: same location, except ‘ 23.vi.2019, Jantarit, S. Prom- dam, R. and Jantapaso, K. leg.’ (5 ♂♂, 9 ♀♀ in NHM-PSU, 6 ♂♂, 4 ♀♀ in SNUC) .

Diagnosis. Body length 2.12–2.26 mm. Vertex with elongate median carina, lateral postantennal carinae absent; clypeus short, less than 1/5 total head length. Pronotum lacking sulci or carinae, with large antebasal spines, sides dentate. Elytra lacking discal striae; anterolateral margins non-emarginate. Metaventrite with narrow notch at middle of posterior margin. Tergite IV with two and sternite IV with four basolateral foveae, each lacking mediobasal fovea. Male antennal club unmodified; profemur ventrally protuberant at basal 2/5; aedeagus asymmetric, with elongate globose basal capsule.

Description. Male ( Fig. 1A ). Length 2.23–2.26 mm. Body uniformly reddish-brown, mouthparts and tarsi lighter in color. Head ( Fig. 2A ) slightly longer than wide, length from clypeal anterior margin to basal construction 0.46 mm, width across eyes 0.43–0.46 mm; dorsum sparsely and finely punctate; vertex with elongate median carina extending from level of vertexal foveae to antennal tubercles, lacking short mediobasal carina; lacking lateral postantennal carinae; clypeus relatively short, slightly less than one-fifth of total head length; each eye composed of about 12 facets ( Fig. 1B ); antennal club formed by three apical antennomeres, which are slightly broader than proceeding antennomeres; antennomere 11 asymmetrically narrowed at apical 1/3. Pronotum ( Fig. 2A ) approximately hexagonal, wider than head and slightly wider than long, length along midline 0.49–0.50 mm, maximum width 0.52 mm; disc sparsely and finely punctate, lacking sulcus or carina, with two large, elongate antebasal spines; sides widest at apical 2/5, distinctly dentate. Elytra slightly longer than wide, length along suture 0.67–0.69 mm, maximum width 0.64–0.65 mm, lacking discal striae, anterolateral margins evenly curved, non-emarginate. Mesoventrite with lateral foveae separated from median foveae. Metaventrite lacking protuberances; posterior margin with narrow notch at middle. Profemur ( Fig. 2B ) ventrally protuberant at basal 2/5. Tergite IV with complete and oblique inner marginal carinae, with complete basal impression ended by two basolateral foveae. Sternite IV with two pairs of basolateral foveae covered under dense setae. Length of aedeagus ( Fig. 2C, 2D ) 0.44 mm; median lobe with stout, elongate basal capsule and large foramen; ventral lobe expanded along left side dorsal-ventrally (natural position) and curved ventrad; dorsal lobe deeply split at base and comprised of two elongate sclerites; parameres attached to apex of basal capsule, reduced to semi-membranous structure.

Female. Similar to male in external morphology, except each eye composed of about 6 facets ( Fig. 1D ) and profemur simple. Measurements (as for male): body 2.12–2.22 mm, length /width of head 0.43–0.48 / 0.39–0.44 mm, length / width of pronotum 0.47 / 0.48–0.52 mm, length / width of elytra 0.62–0.65 / 0.59–0.61 mm, length / width of abdomen 0.60–0.62 / 0.56–0.60 mm.

Comparative notes. The genus Araneibatrus now includes seven species from southern China (5 spp.), northern Laos (1 sp.), and southern Thailand (1 sp.). Using the key provided by Yin et al. (2016) the new species could be keyed out at couplet 3, near A. gracilipes Yin, Li & Zhao 2010 . These two species share a short clypeus and the lack of lateral postantennal carinae of the head, but can be readily distinguished by the presence of large antebasal spines and distinct spinose lateral margins of the pronotum of A. phuphaphet . Beyond that, A. phuphaphet is quite unique among the members of the genus in possessing conspicuously long discal spines of the pronotum, sexually protuberant profemora of the male, as well as a unique, complex structure of the aedeagus.

Biology. Araneibatrus phuphaphet is a cavernicolous species endemic to Phu Pha Phet Cave. The second author and his team have extensively surveyed and collected materials from almost 100 caves in southern Thailand, and in total almost 200 caves throughout the country. However, the new species has been only found in this cave. The populations of A. phuphaphet are rather limited and restricted to the dark zone of certain chambers, with a few individuals being found wandering at the tourist spots. The beetles moved quite fast when disturbed and were usually found roaming around the humid ground floor ( Fig. 3A, 3B ). Araneibatrus phuphaphet prefers an oligotrophic habitat (without bat guano, Fig. 3C, 3D ) where the air temperature is relatively low (24.4–25.2 °C; at altitude 107 m), and the cave soil temperature ranges from 24.4–25.0 °C. The humidity is very high at 93%, with the air at 21% oxygen. During our three surveys we rarely found other micro/macro-invertebrates (except for crickets) in this cave.

Comments. The Phu Pha Phet Cave is the largest cave in Thailand (ca. 20 acres with more than 20 separate rooms) and is ranked the fourth largest in the world. The cave developed in limestone of the Ordovician Thung Song Group, one of the oldest sedimentary rock in Thailand. Unfortunately, little attention has been paid to its fauna. Hence, the discovery of a new cavernicolous pselaphine not only emphasizes the biological importance of the cave and Satun Geopark, but also generates major implications in the development of the conservation policy and ecotourism plan for the area, as well as raising awareness about the unique subterranean environment of the region.

Distribution. Only known from the type locality in Satun Province, southern Thailand.

Etymology. The new specific epithet ‘ phuphaphet ’ is based on the type locality.

Figures

FIGURE 1. Habitus (A, C) and head (B, D) of Araneibatrus phuphaphet sp. nov., lateral. Note the female possesses distinctly smaller eyes than male. Scale bar: 0.5 mm for A, C; 0.2 mm for B, D.

FIGURE 2. Diagnostic features of Araneibatrus phuphaphet sp. nov. male. A. Head dorsum and pronotum. B. Profemur. C, D. Aedeagus, dorsal (C) and lateral (D) (C’ shows apex of ventral lobe in ventral view). Abbreviations: dl = dorsal lobe; pm = paramere; vl = ventral lobe. Scale bar: 0.2 mm.

FIGURE 3. Habitus in situ of Araneibatrus phuphaphet sp. nov. (A, B), and general cave environment (C, D) where the new species was collected.