A review of the Cholevinae from the island of Borneo (Coleoptera, Leiodidae)

Abstract The available knowledge of the round fungus beetle subfamily Cholevinae (Leiodidae) from the island of Borneo is reviewed, and the results of newly studied material presented. The currently known 30 species (of which 14 are newly described herein) represent the genera Micronemadus (one species), Catops (one species), Baryodirus (one species), Ptomaphaginus (14 species), and Ptomaphaminus (13 species). The following new species are described: Micronemadussondaicus Schilthuizen & Perreau, sp. n., Ptomaphaginusgrandis Schilthuizen & Perreau, sp. n., P.louis Schilthuizen & Perreau, sp. n., P.muluensis Schilthuizen & Perreau, sp. n., and P.isabellarossellini Schilthuizen, Njunjić & Perreau, sp. n., and Ptomaphaminuskinabatanganensis Njunjić, Schilthuizen & Perreau, sp. n., P.testaceus Schilthuizen & Perreau, sp. n., P.nanus Schilthuizen & Perreau, sp. n., P.marshalli Schilthuizen & Perreau, sp. n., P.hanskii Schilthuizen & Perreau, sp. n., P.sarawacensis Schilthuizen & Perreau, sp. n., P.layangensis Schilthuizen & Perreau, sp. n., P.microphallus Schilthuizen & Perreau, sp. n., and P.alabensis Schilthuizen & Perreau, sp. n. It is expected that the cholevine biodiversity of Borneo is still far from completely known. Nonetheless, provisional identification keys to all species known so far are presented.


Introduction
Borneo is, after New Guinea, the second-largest tropical island of the world. It has never been strongly isolated, having formed part of a larger land mass, known as Sundaland, during marine transgressions in the Pleistocene (Hall and Holloway 1998). Sundaland comprises the present-day Malay Peninsula, the islands of Sumatra, Java, and Borneo, as well as the shallow seas in between. Recent paleoclimatic modelling (Raes et al. 2014) suggests that even during cooler periods of marine regression, evergreen wet forests dominated the area that now comprises Borneo. This, and the fact that the island, because of its mountainous character (with Gunung Kinabalu reaching almost 4,100 m) contains a great variety of habitats, has generated and maintained a rich biodiversity, not least in its soil and litter-dwelling invertebrate fauna (e.g., Hanski and Hammond 1986, Rahman et al. 2002, Liew et al. 2010. The beetle subfamily Cholevinae (Coleoptera, Staphylinoidea, Leiodidae) consists mostly of small, soil-dwelling scavengers, well represented in the litter fauna of all tropical regions.  provided the first overview of the Cholevinae of South Asia, but the large number of new species described since then (Perreau 2000, and unpublished checklists) mean that this work is severely outdated by now. In recent years, several semi-comprehensive studies have appeared, either limited to a certain region (e.g., Wang and Zhou 2015) or to a certain habitat (e.g., Perreau 2009).
In this paper, we provide an overview of the species of Cholevinae currently known from the island of Borneo. By necessity, this is a very preliminary overview, since it is based on comparatively little information. Jeannel (1936) mentions only one species from Borneo. Szymczakowski (1961) mentions one more, and Peck (1981) and Perreau (2000) describe two more. In 2008, we (Schilthuizen and Perreau 2008) described seven new species and two new records from Borneo, bringing the total cholevine fauna to 13 species. However, more recent work (e.g., Merckx et al. 2015), as well as study of existing material in the Natural History Museum (London), deriving from the 1978 Mulu expedition (Hanski 1983, Hanski andHammond 1986), and in Naturalis Biodiversity Center (Leiden), have revealed many additional new species. In our opinion, the 30 species that we recognize in the present paper form a sufficient basis to produce a first overview of our current, but doubtlessly still very incomplete, knowledge of the cholevine fauna of Borneo.
We provide a brief description for all previously described genera and species, and more extensive descriptions for newly-described species, as well as differential diagnoses for new species that have close congeners in Borneo. Where available, we also refer to DNA sequences in the Barcode of Life Database (BOLD, http://boldystems.org) and to so-called Barcode Index Numbers (BINs; Ratnasingham and Hebert 2013). We also give preliminary identification keys. However, given the fact that this overview is probably still far from complete, these keys should be used with caution: any sample collected in Borneo is likely to contain previously unrecognised species, and we hope this paper will stimulate further taxonomic and faunistic work. Inobong (Crocker Range) and also for the paratypes RMNH.INS.549293-549295 from Gunung Alab (Crocker Range). See also under Remarks.
Habitat and distribution. Very common and widespread, in primary and secondary forest, 0-1850 m elev. In addition to the type material, we have seen seemingly conspecific material from many other localities in Sundaland, (Sabah, Sarawak, Peninsular Malaysia, Mindanao, Java, Bali) and also from Vietnam. Nishikawa's (1989) records of M. pusillimus from Peninsular Malaysia, Sabah, Sarawak, Java, and Bali (which we did not see) may also refer to M. sondaicus. This overview suggests that M. sondaicus is widespread in Southeast Asia (but see below under remarks).
Remarks. For many years, we considered this Borneo Micronemadus, which is usually the commonest leiodid in baited traps, as identical to M. pusillimus. However, DNA-barcodes for Japanese individuals (BOLD BIN ABU9390) and Bornean individuals (BOLD BINs ABU9391 and ACK0008) display a 17% sequence divergence, strongly suggesting that, despite the only slight morphological differences, these belong to separate, not closely related species. We suspect that M. pusillimus, previously considered a very widespread Asian species , may represent a complex of genetically strongly differentiated, but morphologically very similar taxa. In fact, among the DNA-barcoded specimens of M. sondaicus from Sabah's Crocker Range, we already see a 2.7% sequence divergence between highland and lowland populations, which has led the BOLD algorithm to place them into separate BINs (ABU9391 and ACK008, respectively). At the moment, however, we consider ABU9391 and ACK008 as conspecific.
Etymology. The name refers to the Sunda region, of which Borneo forms part (sondaicus (L.) = from Sunda). We used the spelling sondaicus, rather than sundaicus, to conform with other specific epithetons, such as Rhinoceros sondaicus Desmarest, 1822.

Material.
Sabah. Sandakan (leg. W.B. Pryer, NHMUK 1925-264). Holotype of C. solitarius Szymczakowski (examination based on a photograph taken by Jan Růžička). Description. Length: 3.9 mm. Habitus slender and elongated, somewhat flattened. Body reddish brown; head, centre of the pronotum, and centre of the elytra dark brown. Entire dorsum covered in orange setae. Antenna robust, 7 th antennomere as wide as long, 6 th , 8 th , 9 th , and 10 th wider than long. Pronotum 1.54 times as wide as long, frontal and caudal margins straight, lateral margins curved, more strongly rostrad than caudad (greatest width of the pronotum slightly behind the centre), caudal angles broadly rounded; surface with dense, rasp-like punctuation and somewhat matte due to microsculpture. Elytra with fine punctuation, shagreened, and with slight indications of longitudinal striae, 1.27 times as wide as the pronotum, 1.3 times as long as jointly wide (length measured from the caudal tip of the scutellum to the apex of the elytra). Male unknown.
Habitat and distribution. Catops pruinosus is known from a large latitudinal expanse along the East Asian coast: Shanghai, Fujian, and North Borneo. The only known record from Borneo (Sabah: Sandakan) is the female holotype of C. solitarius, later synonymized with C. pruinosus .

Remarks.
Catops pruinosus is a member of the C. hilleri group , represented by ca. 30 species, primarily from central and eastern Asia (Perreau 2000). The diagnosis above is based on a photograph (Figure 2) of the holotype of C. solitarius, as well as the description of C. solitarius by Szymczakowksi (1961). In the absence of males, we are unsure whether the Borneo specimen is indeed conspecific with C. pruinosus. Indeed, we also doubt that the specimen truly derives from Borneo: despite many years of work in Borneo, we have never come across any Cholevini. If members of such temperate-region groups exist in Borneo, we would expect them to occur in the highlands, rather than in coastal locations such as Sandakan. In fact, it is not impossible that the Sandakan specimen is a mislabelled Chinese specimen, as the collector, William Burgess Pryer, was active in Shanghai (where C. pruinosus is known to occur) immediately before moving to Sandakan (Tregonning 1954).
Tribe: PTOMAPHAGINI Jeannel, 1911 Genus: Baryodirus Perreau, 2000 Description. Length: 2.2 mm. Winged and with fully developed eyes ( Figure 3a). Body uniformly brown, eyes black. Dorsal surface with transverse strigae. Pronotal and elytral surface with two types of setation: one dense, long, and recumbent aligned on the transverse strigae, and one sparse, long and erected, roughly aligned along longitudinal rows ( Figure 3b). Head with a high and robust occipital carina. Pronotum convex and transverse, slightly wider than the elytra at the shoulders, 1.9 times as wide as long, the lateral sides rounded, the largest width near the anterior third of the length. Basal margin without a marginal gutter, slightly sinuate near the slightly drawn-out lateral angles. Elytra exactly as long as wide, the largest width at the base. Elytral sides nearly straight, weakly arcuate, giving the elytra a triangular shape. The sutural stria is the only recognizable elytral stria. Mesoventral process strikingly wide and high, anteriorly angular, with flat and setose ventral side, posteriorly widely expanded above the metasternum (Figure 3c). Protibiae with a lateral row of spines along the external edge and with smaller spines randomly arranged on the ventral side ( Figure 3d). Mesotibiae and metatibiae with a circular row of spines around the apex. Female protarsi tetramerous and strikingly expanded with dense setae on the ventral side. Male unknown. Spermatheca elongated with a succession of rings along the entire length (Figure 3e; a somewhat similar condition is found in Ptomaphaminus latescens Szymczakowski, 1964 and P. testaceus sp. n.).

Baryodirus hammondi Perreau, 2000
Figure 3a-e Baryodirus hammondi Perreau, 2000 19-20, figs 1-10; type from Mulu, Sarawak (in NHMUK). Description. See genus description above: the genus is monotypic, and the holotype is the only known specimen of the species. Habitat and distribution. The biotope and ecology of this species are unknown, but several characters suggest that it could be a commensal of hymenopterans. The compact habitus and the double setation are observed (almost exclusively) in many myrmecophilous leiodid genera or subgenera, such as Ptomaphagus (Echinocoleus) Horn in North America, and Synaulus in North Africa (our observations). Portevin, 1914 Description. In Borneo, Ptomaphaginus consists of relatively large Ptomaphagini with four dilated male protarsomeres, distinguishable from Ptomaphaminus by the ventral spines of the protibiae being aligned along the latero-external row of equal spines, making a second, more widely spaced row next to the external one, as well as by the metaventral sutures, which are roughly parallel to the axis of the body. Also, in the female, the gonocoxites are elongated, whereas in most Ptomaphaminus, they are reduced.

Genus: Ptomaphaginus
With Ptomaphaminus Perreau (see below), Ptomaphaginus Portevin makes up the vast majority of the Borneo cholevine diversity. We currently recognise 14 species. However, more diversity is to be expected, both cryptic (e.g., DNA-analysis suggests additional diversity in P. bryanti and related species; Merckx et al. 2015) and non-cryptic (each field project in previously unexplored regions in Borneo results in new discoveries). and a long median processus (the image given by Jeannel [1936] is erroneous, due to mounting error [Schilthuizen and Perreau 2008]).

Ptomaphaginus anas
Differential diagnosis. Very similar to P. bryantioides, from which it differs chiefly (as far as can be discerned from the single P. bryanti individual available) by its more slender habitus.
DNA barcodes. In the BOLD database, COI barcodes are available for RMNH. INS.555591 and 555594, two specimens that possibly belong to this species (See under Habitat and distribution).

Material.
(In addition to that given in Schilthuizen and Perreau (2008) Description. Habitus broad, rectangular, flat, very variable in size, 2.1-3.5 mm. Pronotum on average 1.8 times as wide as long, as wide as the elytra. Elytra as long as wide (length measured from the caudal tip of the scutellum to the apex of the elytra). Winged. Aedeagus with two apical, laterally directed extensions and a long terminal processus. (It appears that in P. bryanti, the lateral extensions may be directed even more ventrad, and the median processus is more widened apically than in P. bryantioides, but the significance of these differences needs to be substantiated.) Male forelegs with long setae on the ventral sides of the femur and tibia. The 3 rd , 4 th , and 5 th visible abdominal ventrite of the male carry a slight central notch and show a depression around these notches. Spermatheca simple, inflated, semicircular (Figure 10a), similar to that of P. louis.
Differential diagnosis. Distinguishable from other Bornean Ptomaphaginus species with the same aedeagus structure by the more elongated aedeagus with long, narrow processus, and the long setae on the male femur and tibia.  (Merckx et al. 2015) shows that within Sabah, several lineages exist. The most widely divergent of these are from Sugud and may represent a separate species (possibly P. bryanti; see above). Additionally, an approximate 4% COI-distance can be observed between the populations on the east and west slopes of the Crocker Range (BOLD BINs ACJ9516+ACJ9517 and ABU8889+ABU8890, respectively), but morphologically these populations are indistinguishable. For the time being, we consider all these BINs as conspecific.
Description. (Adapted from Schilthuizen and Perreau (2008)). Length 2.5 mm. Habitus slender, ovoid. Pronotum 1.7 times as wide as long, slightly broader than the elytra. Elytra slender, 1.25 times as long as their combined width (length measured from the caudal tip of the scutellum to the apex of the elytra). Uniformly light brown. Wingless. Eyes reduced. Elytra laterally not curved, narrowed caudad in an approximately  straight line. Male with a large and deep semicircular depression extended on the 5 th and 6 th visible abdominal sternites, bordered on the front half with long and dense setae, and a central notch on the apical edge of the 6 th . Aedeagus slender. The apex is tapered terminally and ends in a flattened, duck-bill-shaped processus. It carries several long, curved, lateral setae. Differential diagnosis. Unique among the Bornean Ptomaphaginus because of its small, slender build, reduced eyes, and long, slender aedeagus.

Ptomaphaginus caroli
Description. (Adapted from Schilthuizen and Perreau (2008)). Length 2.7 mm. Habitus relatively slender and narrow, flat. Pronotum 1.62 times as long as wide, slightly narrower than the elytra. Elytra 1.41 times as long as their combined width (length measured from the caudal tip of the scutellum to the apex of the elytra). Winged. Long setae on the ventral side of the male profemur and protibia absent. Aedeagus apically with two short 'wings' and a very small, indistinct terminal processus. Spiculum gastrale long-triangular, the apex nearly truncate, with a small central projection; similar in shape to P. latimanus and P. similipes. Differential diagnosis. Ptomaphaginus caroli has a similar aedeagus as P. bryanti, P. similipes, and P. bryantioides. However, it differs in having a distinctly elongated habitus (elytral index of 1.41) and very short apical 'wings' on the aedeagus.
Habitat and distribution. So far, only known from the type specimen, collected in lower montane forest at 1350 m in the Crocker Range of Sabah. The aedeagal shape shows that it belongs within the "bryanti-group".
Remarks. The aedeagus of the holotype has been lost shortly after it was first collected and studied (in 2000). Before the loss, sketches were made of the dorsal and lateral view of the aedeagus, which form the basis for the line drawing in Figure 8 and in Schilthuizen and Perreau (2008).  Paratypes: Sarawak. Mulu National Park, Slope, TPS 7-9, 29.iv.1978(leg. P.M. Hammond & J.E. Marshall, B.M. 1978, 5 males, 7 females; Mulu National Park, Slope, TPS 10-12, v-viii.1978(leg. P.M. Hammond & J.E. Marshall, B.M. 1978, 1 male, 5 females. Description. Habitus: very large (3.4-4.0 mm), dark reddish brown, the elytra deeper red than the pronotum, basis and tip of the antenna pale, antennomeres 5-10 much darker; relatively parallel-sided and somewhat convex, head relatively narrow, pronotum 1.67 times as wide as long, slightly wider than the elytra, caudal angles clearly extended. Elytra of moderate length, convex, broadest at the shoulders, in the caudal one-third gently rounded towards the apex, jointly ca. 1.5 times as long as wide (length measured from the caudal tip of the scutellum to the apex of the elytra). Body entirely covered in dense pale yellow setation. Wings present. Antennae slender, 4 th antennomere longer than wide, 9 th and 10 th antennomere square. Male protarsi only slightly dilated, the first four tarsomeres jointly ca. 4 times as long as wide. Aedeagus short and broad, in lateral view only very slightly bent ventrad with a barely perceptible upturned tip at the end, in dorsal view narrowing (in rounded fashion) towards the blunt apex. Stylet short and straight. Spiculum gastrale long, narrow-triangular, with the caudal part rounded. Spermatheca U-shaped, with ca. 6 distinct narrow rings on the proximate leg of the "U", and ca. 6 additional, indistinct, broader rings on the remainder. Spermiduct long, thin, consisting of 5-6 360° coils.
Differential diagnosis. Externally distinctive by its large size and the colour pattern of the antennae. From equally large P. bryantioides, it may be distinguished by the narrower male protarsi and the longer elytra. Aedeagus cannot be confused with that of any other known Bornean species, but is similar in shape to the one of P. nitens Jeannel, 1936 from Sri Lanka (which, however, is smaller and has much more condensed antennae) and of several species described from China and Taiwan (especially P. pingtungensis Perreau, 1996, P. guangxiensis Wang & Zhou, 2015, P. perreaui Wang & Zhou, 2015, and P. yui Wang & Zhou, 2015, from which P. grandis is distinguished by the unique combination of body size, antennomere proportions, and details of the spiculum gastrale, spermatheca, and aedeagus shape. Habitat and distribution. Only known from Mulu National Park in Sarawak. Etymology. Named grandis for its large size.  (3.3-4.0 mm), winged. Elytra, legs and basis and tip of the antennae dark reddish brown, pronotum, head and antennomeres 5-10 nearly black. Pronotum 1.6 times as wide as long, caudal angles clearly extended, as wide as the elytra at the shoulders. Elytra slender, slightly convex, 1.5 times as long as wide (length measured from the caudal tip of the scutellum to the apex of the elytra). Elytral apex in the female gradually rounded and joining the suture at a right angle; in the male more acute, meeting the suture at a sharp angle, and with a distinct bunch of thick, black, outwardly-curved, spine-like setae. Wings present. Body otherwise covered with dense light grey setation. Male tarsi strongly dilated, tarsomeres 1-4 jointly twice as long as wide. Female tarsi not dilated. Aedeagus very strongly curved ventrad, very convex, with a distinct dorsal keel; apex trilobate; stylet very long and thin, hair-like. Spermatheca semicircular, spermiduct extremely long (in extended condition probably at least 5 mm), consisting of ca. 30 360° loops.

Ptomaphaginus isabellarossellini
Differential diagnosis. Among Sabah Ptomaphaginus, and more generally, very distinctive by its large size, dark colouration (but see below under Remarks), the spine-like setae on the male elytral apex, and the uniquely shaped aedeagus (the basic design of which, with two lateral flaps at the apex, resembles that of the P. bryanti group, as well as non-Bornean species like P. sinuatus Schilthuizen, 1984). The conspicuous bunch of spines at the elytral apex in the male is shared with three other non-Bornean species, viz. P. riedeli Perreau, 1995, P. pilipennis Perreau, 1991and P. pilipennoides Perreau, 1991, which, however, differ strongly from P. isabellarossellini in aedeagal shape. In other Bornean species, P. bryantioides and P. similipes, stronger setae at the male elytral apex can also be discerned, but never as conspicuous as in P. isabellarossellini.

Habitat and distribution. Only known from the lower montane forest around Kinabalu Park Headquarters.
Remarks. It should be noted that specimens of the normally rusty-coloured P. scaphaner Szymczakowski, 1972 from the same collection sample as P. isabellarossellini are also nearly black. This may mean that the dark colouration of P. isabellarossellini is a preservation artefact.
Etymology. Named in honour of the actress and biologist Isabella Rossellini, whose short movies and stage performances on animal reproduction have popularized theories on the evolution of genitalia. In P. isabellarossellini, the extremely long penis stylet in the male and similarly long spermiduct in the female suggest a long history of sexually antagonistic coevolution, one of the types of selection that appears in Rossellini's 'Green Porno' series on SundanceTV (Schilthuizen 2014).

Material. (In addition to that given in Schilthuizen and Perreau
Differential diagnosis. Similar in aedeagal shape to P. bryantioides, but very different in habitus, which is more slender in P. kinabaluensis. Furthermore, P. kinabaluensis has only slightly dilated male protarsi, no setae on the male profemur and protibia, and extended elytral apices in the female.   (2008)). Length 2.3-2.9 mm. Habitus slender, ovoid. Pronotum 1.60-1.75 times as wide as long, as wide as the elytra. Elytra 1.15-1.25 times as long as their combined width (length measured from the caudal tip of the scutellum to the apex of the elytra). Winged. Aedeagus short and wide, with two elongated apical, laterally-directed 'wings' and a short terminal processus. Spermatheca narrow, annulated, and bent over a rounded 90° angle, quite similar to that of P. kinabaluensis. Spermiduct long and narrow, with numerous coils. Antennae short, as long as the width of the head. Long setae on the ventral side of the male profemur and protibia absent. Male with broad and indistinct central notches on the 5 th and 6 th visible abdominal sternite. Male protarsi strongly dilated. Differential diagnosis. Ptomaphaginus latimanus is closely related to P. kinabaluensis, but differs in the habitus, which is much more stocky in P. latimanus. Also, P. kinabaluensis has extended elytral apices in the female, less strongly dilated male protarsi, and a central extension on the male 4 th abdominal sternite.

Habitat and distribution.
Only known from montane forest at Gunung Trusmadi in Sabah, at 1400 m elev. One bryanti-group female (RMNH.INS.555611) from Sayap substation on Gunung Kinabalu is genetically unique (BOLD BIN: ACK0183) and might also belong to this species. Description. Length 2.0-2.8 mm. Habitus: Light to dark reddish brown; flattened and relatively short and broad, head broad, pronotum 1.6-1.7 times as wide as long, narrower than the elytra, caudal angles almost not extended. Elytra short, gently convex, jointly ca. 1.2 times as long as wide (length measured from the caudal tip of the scutellum to the apex of the elytra). Body entirely covered in dense golden-yellow setation. Wings present. Antennae slender, 4 th , 9 th , and 10 th antennomeres almost as long as wide. Male protarsi slightly dilated, the first four tarsomeres jointly ca. 3.5 times as long as wide. Aedeagus gently bent ventrad, flattened, apically broad and convex but subapically tapering in a rounded fashion into a broad but sharp upturned tip. Stylet long and thin, hair-like; stored in a wide loop in the basal part of the aedeagus. Spiculum gastrale elongate-ovoid, with the caudal part button-shaped, truncated. Spermatheca semicircular, thick, otherwise featureless, "sausage-shaped". Spermiduct long, thin, consisting of ca. 4-6 360° coils. Differential diagnosis. Aedeagus in dorsal view very similar to that of P. tarsalis Symczakowski, 1964 from Sumatra, but in lateral view apically clearly more convex and with a shorter stylet. Moreover, the habitus and appendages of P. tarsalis are very stout and thick, whereas those in P. louis are much more slender. Also very similar to P. muluensis, but externally distinguished by the smaller size and more stocky habitus, with shorter elytra, narrower pronotum and the absence of drawn-out caudal pronotal angles. Aedeagus in dorsal view tapering abruptly towards the apex, not as gradually as in P. muluensis; in lateral view, the apex is more convex. Spermatheca distinguished from P. muluensis by the semicircular shape without any distinctive rings.

Ptomaphaginus louis
Habitat and distribution. Only known from Mulu National Park, Sarawak. Remarks. Two females from the Mulu locality "Slope" have several rings at the basis of the spermatheca. As they are externally identical to other females of this species, they have been provisionally included in this species, but excluded from the type series. Several specimens infected on the elytra and pygidium with black Laboulbeniales.
Etymology. We name this species after our friend and colleague Dr. Louis Deharveng (MNHN), in recognition for his logistic and emotional support during the preparation of this paper. The specific epithet is given as a noun in apposition. Description. Length 2.5-3.1 mm. Habitus: reddish brown; relatively parallel-sided and somewhat flattened, head broad, pronotum 1.6 times as wide as long, as wide as the elytra, caudal angles clearly extended. Elytra of moderate length, gently convex, in the caudal one-third gently rounded towards the apex, jointly ca. 1.4 times as long as wide (length measured from the caudal tip of the scutellum to the apex of the elytra). Body entirely covered in dense golden-yellow setation. Wings present. Antennae slender, 4 th , 9 th , and 10 th antennomeres slightly wider than long. Male protarsi slightly dilated, the first four tarsomeres jointly ca. three times as long as wide. Aedeagus gently bent ventrad, in lateral view apically flattened and ending in a bulbous upturned tip, in dorsal view gradually narrowing towards the apex. Stylet long and thin, hair-like.

Ptomaphaginus muluensis
Spiculum gastrale long-ovoid, with the caudal part truncated. Spermatheca J-shaped, with 7-10 narrow rings on the long shaft of the "J", and 5-7 broader rings on the curved part. Spermiduct long, thin, consisting of at least ten 360° coils.
Differential diagnosis. Very similar to P. louis, but externally distinguished by the larger size and more slender habitus, with longer elytra, broader pronotum and distinctly drawn-out caudal pronotal angles. Aedeagus in dorsal view tapering gradually towards the apex, not as abruptly as in P. louis; in lateral view, the apex is not as convex. Spermatheca distinguished from P. louis by the J-shape with distinctive rings.
Habitat and distribution. Only known from Mulu National Park, Sarawak. Several specimens infected with black Laboulbeniales on the elytra and the pygidium.
Etymology. Named after Mulu National Park, to date the only locality from which this species is known.

Ptomaphaginus sabahensis Schilthuizen & Perreau, 2008
Figures 5g, 7i, j, 9h Ptomaphaginus sabahensis Schilthuizen & Perreau, 2008: 202, figs 11, 12; type from Gunung Kinabalu, Sabah, Borneo (in MHNG). (2008) Habitus broad and short, colouration light reddish-brown. Pronotum 1.75 times as wide as long, slightly narrower than the elytra. Elytra 1.2 times as long as jointly wide (length measured from the caudal tip of the scutellum to the caudal tip of the elytra). Wings present. Antennae very broad and short, with antennomeres 9 and 10 twice as broad as long. Aedeagus strongly curved, extremely convex and swollen, ending in a flattened "beak"; stylet long and thin, hairlike, running along the inside of the roof of the convex part of the aedeagus. Spiculum gastrale short, triangular, as long as wide. Spermatheca U-shaped, with 6-7 broad rings along the proximal part, and ca. 5 much narrower rings in the terminal one-quarter. Spermiduct very long and very thin.

Description. (adapted from Schilthuizen and Perreau
Differential diagnosis. Unique among the Bornean Ptomaphaginus by the condensed antennae and the inflated aedeagus with flattened "beak" and long stylet. Habitat and distribution. This appears to be a very widespread species, now known from Vietnam, Peninsular Malaysia, Borneo, and Java. It is possible, however, that the species consists of a complex of closely related species, given the geographic variation in secondary sexual characters (Schilthuizen and Perreau 2008).

Ptomaphaginus similipes Schilthuizen & Perreau, 2008 Figures 5d, 6e, f, 9l
Ptomaphaginus similipes Schilthuizen & Perreau, 2008: 193-194, figs 18-19, 27-28; type from Crocker Range Park, Sabah, Borneo (in RMNH). (2008) Description. Length 2.4-3.0 mm. Pronotum 1.69-1.80 times as wide as long, as wide as the elytra. Elytra 1.19-1.23 times as long as wide (length measured from the caudal tip of the scutellum to the apex of the elytra). Wings present. Aedeagus short and broad, with two short apical, laterally directed 'wings' and a short terminal processus. Male forelegs usually with long setae on the ventral side of the femur and tibia. Male protarsus completely not dilated, of the same width as in the female. The 3 rd , 4 th , and 5 th visible abdominal ventrite of the male carry a slight central notch and show a depression around these notches. Spermatheca narrow, V-shaped, with ca. 10 indistinct rings. Spermiduct long and thin, consisting of ca. 6 360° loops.

Material. (In addition to that given in Schilthuizen and Perreau
Differential diagnosis. Among other members of the P. bryanti complex, distinguished by the not dilated male protarsi, thin, annulated spermatheca, the relatively small size, and the short and squat aedeagus. have not yet been able to extract amplifiable DNA from these. Habitat and distribution. Appears to be widespread on the west coast of Sabah and Sarawak, at elevations between 350 and 1400 m. Some deep molecular divergences are apparent: the specimens collected at Sayap fall in a different DNA barcode BIN than the ones from Sugud (BOLD BINs ACK0140 and ACK0141+ABV4636).
Remarks. The male protarsi were slightly dilated in the one male from the Kinabalu Headquarters area.

Notes.
During the study of this Bornean material, we have refined our concept of the genus Ptomaphaminus, which is why the genus description below is more extensive than for the previous genera.
Description. Species of small size, not exceeding 2 mm. Colour generally brown, partly yellowish or light brown, rarely darker. Dorsal surface covered with short recumbent setae inserted along transverse strigae which also cover the whole dorsum of the body. Head with more or less developed eyes. A significant eye reduction is observed in species living in subterranean environments. Antennae generally slender, the apical club weakly marked. Pronotum transverse, the largest width generally at the base, the sides of the pronotum and the elytra continuously arcuate, of equal width. Elytra generally elongate, the posterior sutural angles rounded in males (Figure 14a), in females either rounded (Figure 14b), or simply angular (Figure 14c), or sharply protruding backwards (Figure 14d-e). Surface of elytra with transverse oblique strigae and a single longitudinal sutural stria. Flight wings generally present and functional, even in species living in subterranean environments. (The few apterous or brachypterous species of the genus do not live in Borneo.) Mesoventral process low, narrow, and rounded. Metasternal sutures incomplete and convergent towards the central axis of the body. Protibiae with a lateral row of spines along the external edge and with smaller spines randomly dispersed on the ventral side. Mesotibiae and metatibiae with a circular row of spines around the apex. Male protarsi with four protarsomeres expanded, female protarsi unexpanded. Male and female mesotarsi and metatarsi unexpanded. Male genital segment (urite IX) with a long spiculum gastrale, significantly extending beyond the anterior margin of the epipleurites and sometimes expanded into a paddle shape in the distal half. The size of the aedeagus (relatively to the body length) is highly variable: from 3.0 (P. latescens) to 5.7 (P. marshalli) times smaller than the body length. The left apical expansion of the median lobe generally (in Borneo species) with a more or less developed, ventrally deflexed and sometimes retroverted apical hook, clearly visible in lateral view, more rarely simple (P. latescens, P. testaceus sp. n.). Endophallus with a long and weakly sinuate stylus and with a basal symmetric (Figures 12a, 12c) or asymmetric (Figures 12f, h, j, l, m, o, q, s, w, y) loop. When asymmetric, the loop is expanded on the left side in dorsal view (which appears on the right side on pictures which are traditionally illustrated with the caudal side up). Female genital segment either with long gonocoxites, more than three times as long as wide (P. latescens: Figure 13b; P. testaceus sp. n.: Figure 13d), or gonocoxites reduced to small subsquare sclerites (Figures 13f, h, j, n, p, s, u). Spermatheca generally bilobate, with (P. ater Perreau, 2009: Figure 13f ) or without an apical sclerified plate. A single lobe, weakly sclerotised and transversally ringed occurs in P. latescens ( Figure 13b) and P. testaceus (Figure 13d). Spermiduct less sclerotised, but generally with a fixed morphology, sometimes wrapped in a helical shape, rarely entirely membranous, without structured morphology (P. hanskii sp. n., P. sarawacensis sp. n.: Figures 13h-13j).
Remarks. The two species P. latescens and P. testaceus sp. n. have significantly different morphological characters from other species of Ptomaphaminus (not limited to Borneo): a short stylus of the endophallus (limited to half the length of the median lobe) with a symmetric basal loop, female gonocoxites long (more than three times longer than wide), a weakly sclerified spermatheca with a set of transversal rings (similar to structures preventing a collapse under depression, like for the respiratory trachea). Other species have a long stylus developed on most of the length of the aedeagus, female gonocoxites short, sub-square and a more sclerified spermatheca without reinforcing transversal rings. These two species form a distinct species group which possibly represents another genus.
Biology. Little information is available on the biology of Ptomaphaminus. Two methods of sampling are successful in obtaining specimens: trapping with pitfall traps baited with meat, cheese, or human excrement (either in epigean or in cave environments) and manual collecting in caves. Species collected in epigean conditions generally have fully developed eyes and flight wings while specimens from caves often have reduced eyes (although presently no anophthalmic Ptomaphaminus are known). The eye reduction observed in species recorded from caves is not correlated with the flight wing reduction, in contrast to palaearctic and nearctic subterranean species of Cholevinae (Leptodirini; Ptomaphagus (Adelops)). Flight wings of P. fagei Perreau, 2009 andP. latescens Szymczakowski, 1964, for example, remain fully functional as observed in Gua Sedepan (Eastern Kalimantan) and caves in the Kinabatangan valley (Sabah) where specimens flew up when lighted by headlamps even in the dark zone deep inside caves. A similar observation was reported by Peck (1981) for P. chapmani Peck, 1981. Species are very similar externally. For each of the species below, we provide only specific diagnoses, without listing any shared generic characters.  , viii.1924 (leg. E. Jacobson, ZMA.INS.1229106, 1229112, 1229124, 1229126, 1229128, 1229135, 1229147-1229149, 1229151, 1229153, 1229154), 12 paratypes.
Description. Length 1.45-1.75 mm. General colour dark brown. Winged. Eyes normally developed. Pronotum 1.56 times as wide as long. Elytra 1.35 times as long as wide. Female sutural angle of elytra expanded backwards into a sharp tooth. Male protarsi 0.5 times as wide as the protibia. Male genital segment with a very elongate and thin spiculum gastrale (Figure 13a). Aedeagus three times shorter than the body length, strikingly elongate and parallel-sided (Figure 12b). Apex of the median lobe rounded, with two overlapping apical right and left expansions in dorsal view (Figure 12b), regularly arcuate and without apical hook in lateral view (Figure 12a). Two lateral setae on each side, orthogonal to the plane of the aedeagus. Internal stylus of the endophallus short and strongly sinuate, confined to the apical half of the length of the median lobe. Female with normally developed gonocoxites (Figure 13b). Spermiduct irregularly wound, not clearly helical. Spermatheca weakly sclerotised, the apical capsule with a set of transversal rings and without apical sclerotised plate (Figure 13b). Differential diagnosis. Larger than most other Bornean Ptomaphaminus, with spiniform elytral apices in the female, and a very narrow urite IX in the male; differing from the otherwise similar P. testaceus by the darker head and discus of the elytra, as well as slight differences in the aedeagus.
DNA barcodes. COI barcodes are available for the following specimen: RMNH. INS.555607 (Kinabalu Park HQ), BIN: ACJ9972. The specimens RMNH. INS.549312-549316 have entries in BOLD, but we have so far been unable to extract amplifiable DNA from them.

Ptomaphaminus testaceus
Description. Length: 1.4-1.8 mm. General colour light reddish brown; legs, antenna, and mouthparts yellowish. Winged. Eyes well developed. Pronotum 1.45 times as wide as long. Elytra 1.45 times as long as wide. Female sutural angle of elytra expanded backwards into a sharp tooth. Male protarsi 0.4 times as wide as the apex of protibia. Male genital segment with a very elongate thin spiculum gastrale (Figure 13c). Aedeagus approximately 3.25 times shorter than the body length, elongate and parallel-sided, apex rounded, with two overlapping apical right and left expansions in dorsal view (Figure 12d), regularly arcuate from base to apex, without apical hook in lateral view (Figure 12c). Two lateral setae on each side, orthogonal to the plane of the aedeagus. Internal stylus of the endophallus short and strongly sinuate, confined to the apical half of the length of the median lobe (Figure 12c). Female genital segment with normally developed gonocoxites. Spermiduct slightly helical. Spermatheca weakly sclerified, with a set of transverse rings and without apical sclerotised plate (Figure 13d). Differential diagnosis. Very similar to P. latescens, but distinct in the external morphology by its significantly smaller size, and its lighter colour. The spermiduct is slightly helical, which is not the case in P. latescens.
Habitat and distribution. Known only from the lowland forest of Gunung Mulu, Sarawak, Malaysia.

Ptomaphaminus ater Perreau, 2009
Figures 12e Description. Length 1.75-2.00 mm. Large species, dark brown, winged. Eyes reduced, with 25 ommatidia. Pronotum ca. 1.5 times wider than long. Elytra approximately 1.2 times longer than wide. Female apex of the elytra with a sharp sutural angle expanded posteriorly (Figure 14d). Male protarsi approximately 0.6 times as wide as the apex of protibia. Male genital segment with long and apically expanded spiculum gastrale, widely dilated into a kind of paddle (Figure 13e). Aedeagus long, 3.5 times shorter than the body length, parallel-sided, straight, shortly narrowed near the apex in dorsal view (Figs 12f ), ventrally bent on the last quarter of its length and with an apical hook clearly retroverted ventrally (Figure 12g). Stylet of the endophallus long and straight. Female genital segment with reduced gonocoxites. Spermiduct helical. Spermatheca long, bilobate, rounded at the apex, but with an apical sclerotised plate (Figure 13f ).
DNA barcodes. For two individuals, RMNH.INS.555623-555624, COI barcodes are available in BOLD, which form the BIN ACK0013.

Habitat and distribution.
Known from high altitude on Gunung Kinabalu, above 3000 m. Some specimens were taken under a rocky overhang (Paka cave), others in Panar Laban (type locality) and Gunting Lagadan, without detail on collecting conditions.
Remarks. The only species in Borneo with an apical sclerotised plate at the apex of the spermatheca (which occurs in several other species outside Borneo). Description. Length: 1.45-1.60 mm. General colour brown; antenna, mouthparts, and protarsi yellowish, the other tarsi light brown. Winged. Eyes well developed. Pronotum 1.55 times wider than long. Elytra 1.25 times longer than wide (slightly wider in males than in females). Female sutural apex of elytra angular but not protruding backwards. Male protarsi 0.65 times as wide as the apex of protibia. Spiculum gastrale of the male genital segment shortly protruding beyond the apex of epipleurites, significantly dilated ( Figure 13m). Aedeagus approximately 4 times smaller than the body length, parallel on the first third of its length, then regularly narrowed, the sides linearly convergent towards the apex in dorsal view ( Figure  12u), straight in lateral view (Figure 12v). Apex of the median lobe with a long hook deflexed towards the ventral side, but not retroverted in lateral view ( Figure  12v). Six lateroventral preapical setae on each side. Internal stylus of the endophallus long and moderately sinuate. Female genital segment with reduced gonocoxites. Spermiduct not helical. Spermatheca rounded at the apex without sclerotised plate (Figure 13n). Differential diagnosis. Female with spiniform elytra; male with long apical hook of the (relatively short but straight) aedeagus, which, however, is not retroverted.

Ptomaphaminus kinabatanganensis
Habitat and distribution. Known exclusively from three caves in the lower Kinabatangan valley: Gua Babi, Gua Fico, and Gua Ikan.

Ptomaphaminus chapmani (Peck, 1981) Figures 12g-h, 13r-s, 14e
Ptomaphaginus chapmani Peck, 1981. Peck (1981 fig. 1-4) Winged. Eyes with ten ommatidia. Pronotum 1.47 times as wide as long, elytra 1.84 times as long as wide. Female sutural angle of elytra expanded in a sharp apical tooth (Figure 14e). Protarsi 0.8 times as wide as the protibia. Spiculum gastrale of the male genital segment moderately dilated in a parallel-sided spatula (Figure 13r). Aedeagus long, approximately 3.3 times smaller than the body length, parallel, weakly arcuate in lateral view and shortly narrowed on the apical quarter of its length, rectangular at the apex, with an apical hook strongly retroverted ventrally (Figure 12g, h). Internal stylus of the endophallus long and straight. Female genital segment with reduced gonocoxites. Spermiduct not helical. Spermatheca rounded at the apex without sclerotised plate (Figure 13s). Differential diagnosis. Unique among Bornean Ptomaphaminus in showing a combination of troglomorphic features: reduced eyes and elongated habitus. Aedeagus very similar to that of P. ater, which, however, is darker and has a more strongly cuneiform habitus.
Habitat and distribution. Known only from a single cave (Clearwater cave) in Gunung Mulu, Sarawak, Malaysia.

Ptomaphaminus fagei Perreau, 2009
Figures 12q-r, 13k-l Ptomaphaminus fagei Perreau, 2009. Perreau (2009 . 4)  a triangular apical part (Figure 13k). Aedeagus 4.8 times as long as the body length, parallel-sided at the base, triangularly narrowed in the last third of the length in dorsal view (Figure 12q), thick at the base, abruptly thinned in the two apical third of its length and ending with a short ventrally deflexed hook in lateral view (Figure 12r). Five lateroventral lateral external setae and three more ventral central setae on each side. Internal stylus of the endophallus straight. Parameres with five apical external and three apical internal setae. Female genital segment with reduced gonocoxites, spermatheca bilobate, with helicoidal spermiduct, and without apical sclerotised plate (Figure 13l).
Differential diagnosis. Among the species with similarly reduced eyes and/or spiniform female elytral apices, P. fagei is unique in having an aedeagus that shows an abrupt narrowing (in lateral view) in the apical third.

Ptomaphaminus nanus
Description. Length: 1.28-1.50 mm. General colour brown; tarsi, antenna, mouthparts yellowish. Winged. Eyes well developed. Pronotum1.6 times as wide as long. Elytra 1.2 times as long as wide. Elytral internal angle rounded in male and in female, without noticeable sexual dimorphism. Male protarsi 0.6 times as wide as the protibia. Spiculum gastrale of the male genital segment dilated into a narrow spatula (Figure 13t). Aedeagus approximately 4.7 times smaller than the body length, slightly arcuate in lateral view and the sides slightly arcuate in dorsal view, the apex with a short ventrally deflexed hook (Figures 12m, 2n). Internal stylus of the endophallus long and nearly straight. On each side one lateroventral preapical seta, one lateroapical, and one seta located at the apical third of the length of the aedeagus. The lateroapical seta is pointing forward, the other orthogonally to the plane of the aedeagus. In addition, there are two very strong preapical setae on each side, which have no equivalent in other species. Female genital segment with reduced gonocoxites. Spermiduct helical with a very large number of tightly compacted coils. Apex of the spermatheca rounded, without apical sclerotised plate (Figure 13u).
Differential diagnosis. Small-sized species with normally developed eyes and non-spiniform female elytra. Spermiduct tightly coiled; aedeagus small; distinguishable from P. marshalli, which has an equally small aedeagus, by the very short hook.
Habitat and distribution. Known from lowland forests of Gunung Mulu, Sarawak, Malaysia.

Ptomaphaminus marshalli
Habitat and distribution. Known from lowland forests of Gunung Mulu, Sarawak, and of Gunung Kinabalu, Sabah, Malaysia. Etymology. Dedicated to J. E. Marshall, one of the collectors of the species during the expedition of the Natural History Museum of London in Sarawak.
Habitat and distribution. Known from lowland forests of Gunung Mulu, Sarawak, Malaysia.
Remarks. The external morphology and the female genital morphology are extremely similar to P. sarawacensis, so that females are nearly impossible to distinguish. However, the male aedeagi of these species are very different.

Ptomaphaminus sarawacensis
Description. Length: 1.90-2.35 mm. General colour brown; the tarsi and two first antennomeres yellowish. Winged. Eyes well developed. Pronotum 1.6 times as wide as long. Elytra 1.4 times as long as wide. Sutural angle of female elytra angular (Figure 14c). Apex of the spiculum gastrale of the male genital segment dilated into a paddle-like shape (Figure 13g). Aedeagus approximately four times shorter than the body length. Median lobe parallel-sided in the first half, then regularly narrowed from the middle of its length, with a preapical constriction in dorsal view (Figure 12j), obtusely angular ventrally after the middle, with a long apical ventrally deflexed but not retroverted hook in lateral view (Figure 12i). Six lateroventral preapical setae and one lateroapical seta on each sides. Internal stylus of the endophallus nearly straight. Female genital segment with reduced gonocoxites. Spermiduct membranous, vaguely helical at least near the base of the spermatheca. Apex of the spermatheca rounded, without apical sclerotised plate (Figure 13h) Description. Length: 1.6-2.5 mm. General colour dark brown; the tarsi and two first antennomeres lighter. Winged. Eyes well developed. Pronotum 1.6 times as wide as long. Elytra 1.45 times as long as wide. Sutural angle of female elytra rounded, without noticeable sexual dimorphism. Male protarsi 0.75 times as wide as the protibia. Spiculum gastrale of the male genital segment short, moderately dilated at the apex (Figure 13o). Aedeagus 5.4 times shorter than the body length, the sides regularly arcuate in dorsal view (Figure 12s), ventrally straight and dorsally obtusely angular in lateral view. Apex of the median lobe with a ventrally deflexed, arcuate hook in lateral view (Figure 12t). Six lateroventral preapical setae and one lateroapical seta on each side. Internal stylus of the endophallus significantly sinuate. Female genital segment with reduced gonocoxites. Spermiduct long and helical (Figure 13p). Apex of spermatheca rounded, without apical sclerotised plate.
Differential diagnosis. Normal-sized species with unreduced eyes and non-spiniform female elytra. Aedeagus with a long, retroverted apical hook. Distinguishable from P. alabensis by the anteriorly widened spiculum gastrale and the broader apex of the median lobe of the aedeagus. Females are distinguishable from P. nanus by their larger size.
DNA Description. Length: 1.2 mm. General colour dark brown; the tarsi and two first antennomeres lighter. Winged. Pronotum 1.55 times as wide as long. Elytra 1.15 times as long as wide. Male protarsi 0.6 times as wide as the protibia. Spiculum gastrale of the male genital segment apically dilated into a short discoid expansion (Figure 13q). Aedeagus very small, 5.5 times shorter than the body length. Lateral sides regularly arcuate in dorsal view (Figure 12y), flattened in the middle and with a short ventrally retroverted expansion in lateral view (Figure 12z). On each side, six latero-preapical pointing ventral setae and one apical seta pointing forward. Internal stylus of the aedeagus weakly sinuate.
Differential diagnosis. The female is unknown, but the male aedeagus shares several features with other species, such as P. marshalli, P. nanus, and P. alabensis (i.e., a relatively short aedeagus with retroverted hook). However, P. microphallus is unique among Borneo Ptomaphaminus by its extremely short (0.22 mm) aedeagus.
Habitat and distribution. Known from the type locality, in Kinabalu Park, Sabah, Malaysia.
Remarks. Female unknown. Etymology. Named for the relatively small male genitalia.  Schweiger 3 Female protarsi tetramere and widely dilated (Figure 3d), approximately as wide as the apex of the protibia. Mesoventral process extremely wide and high with a flat ventral side (Figure 3c). Pronotal and elytral setae of two kinds, one long and erect, the other short and recumbent (Figure 3a)  Aedeagus with two lateral "flaps" at the apex and usually a median processus, the apex thereby appearing bilobate or trilobate (Figs 6a, c Aedeagus apically with two long lateral flaps that jointly are more than half the width of the basal part of the aedeagus, and a long median processus. Antennae short and broad, antennomeres 9 and 10 twice as long as wide; aedeagus inflated and strongly convex; spermatheca with multiple ring-shaped constrictions (Figure 10f )  Terminal lobe of spermatheca regularly narrowed, the apex conical (Figure 13y)