Review of Dolichostyrax Aurivillius (Cerambycidae, Lamiinae) in Borneo, with descriptions of three new genera and the first case of (ovo)viviparity in the long-horned beetles

Abstract We reviewed the species of genus Dolichostyrax Aurivillius (Cerambycidae: Morimopsini) from Borneo, which included the redescriptions of two species – Dolichostyrax moultoni Aurivillius, 1911 and Dolichostyrax longipes Aurivillius, 1913, with the first female description for the latter. After the examination of the additional material previously identified as Dolichostyrax, we described three new genera – Borneostyrax gen. n., Microdolichostyrax gen. n., and Eurystyrax gen. n. Borneostyrax cristatus sp. n. was described based on the male and female specimens, whilst Microdolichostyrax hefferni sp. n., Microdolichostyrax minutus sp. n. and Eurystyrax nemethi sp. n. are known only from females. All studied species are distributed in the mountain regions of Sabah, with the exception of Dolichostyrax moultoni from Sarawak. An identification key to the genera of Bornean Morimopsini and species of Dolichostyrax, Borneostyrax gen. n., Microdolichostyrax gen. n. and Eurystyrax gen. n. is provided and their distributions and intraspecific morphological variability are discussed. The short and wide ovipositor, loss of spermatheca, and presence of large larvae without apparent eggbursters inside the female abdomens indicate the presence of (ovo)viviparity in Borneostyrax gen. n. This is the first case of this rare phenomenon within Cerambycidae.


Introduction
Long-horned beetles (Cerambycidae) with about 35,000 described species are the fifth largest beetle family in the world (Švácha and Lawrence 2014). Although they are widespread, well-known, easily recognized and intensively collected by both amateurs and professional entomologists, their classification is still not well understood. For example, Lamiinae forms by far the most species-rich cerambycid subfamily, however, almost nothing is known about their interrelationships. Many supraspecific taxa are only vaguely defined, and a complete revision of the tribal classification is deeply warranted (Ślipiński and Escalona 2013). Morimopsini is most probably a polyphyletic lineage currently containing about 200 species classified in 50 genera distributed mainly in the tropical areas of Africa and Asia (e.g., Breuning 1950, Sudre and Teocchi 2002, Vitali and Menufandu 2010, Nearns et al. 2015, Tavakilian and Chevillotte 2015, Weigel 2015. Three small genera are reported from Borneo: endemic Anexodus Pascoe (two species) and Pantilema Aurivillius (monotypic), and Dolichostyrax Aurivillius (two species; with remaining congeners known also from Java and Sumatra) (Breuning 1950). Members of these genera are flightless and inhabit the leaf litter in rain forests. They are only rarely collected and there is absolutely no information on their morphological inter-and intraspecific variability, immature stages, distribution, relationships, biology, and ecology. Breuning (1950) made a generic and species identification key and since then, no attention was paid to the Bornean Morimopsini except for an isolated description of a new Anexodus by Sudre (1997).
Herein, we review the Dolichostyrax species in Borneo, which includes the redescriptions of D. moultoni Aurivillius, 1911 andD. longipes Aurivillius, 1913 and the descriptions of three new genera closely related to Dolichostyrax. For the first time, male and female genitalia are investigated and the identification key is provided for the Bornean Morimopsini.

Material and methods
The study is based on adult semaphoronts of both sexes. Before the investigation of the external morphological characters, specimens were cleaned from a crust of dirt in a sonicator, following the method of Harrison (2012). The genitalia of both sexes were briefly kept in hot 10% KOH, dissected, transferred to glycerol and subsequently photographed using a Zeiss Discovery.V12 with ZEN software. The line illustrations were derived from the photographs. All dissected parts were mounted on the separate cardboards using the DMHF (Dimethyl Hydantoin Formaldehyde) resin and pinned with specimens. The measurements of taxonomically relevant morphological structures were taken with a measuring tool in ZEN software. The following abbreviations were used: BL -body length, measured from the fore margin of head to the apex of elytra; BW -maximal body width. Data from the locality labels are cited verbatim. A slash (/) is used to separate lines on the same label and a double slash (//) is used to separate different labels on the pin. The morphological terminology follows those of Ślipiński and Escalona (2013) and Švácha and Lawrence (2014). Dolichostyrax Aurivillius, 1911: 194. Dolychostyrax Breuning, 1950.
Prothorax 1.1 times as long as wide, laterally with one small obtuse tubercle; pronotal disc with a pair of distinct tubercles near middle and one median at second half; pronotal tubercles not punctured. Prosternum in front of coxae 0.7 times shorter than diameter of coxal cavity. Scutellum transverse, about four times as wide as long. Elytra elongate, 1.6 times as long as wide at widest part, 1.9 times as long as pronotum, widest before middle; each elytron with three rows of tubercles irregular in shape and size (Figs 1, 2), sparsely covered with large deep punctures arranged irregularly in rows, more distinct near elytral suture. Legs long, slender; tibial spurs with mesotibial ones inconspicuous; protarsi and left mesotarsus preserved with tarsomeres I-II only, metatarsus with tarsomere I only; relative lengths of metatarsomeres 1.0 : 1.0 : 1:3 : 2.1.
Redescription of holotype (male). BL 9.4 mm, BW 3.5 mm. Body black, antennae and legs slightly lighter. Body densely clothed with very short golden brown pubescence, incorporating fine detritus particles. Head about as wide as anterior margin of pronotum. Antennae 1.3 times longer than body length; scape gradually only slightly widened towards apex, apical part distinctly thicker than the rest of scape, forming a distinct bulge (Fig. 16), densely covered with very short light brown pubescence; the relative ratio of antennomere lengths 2.5 : 0.3 : 1.0 : 1.0 : 0.8 : 0.7 : 0.6 : 0.6 : 0.6 : 0.6 : 0.8.
Prothorax as long as wide, laterally with one indistinct tubercle; pronotal disc with a pair of indistinct tubercles near middle and one median at second half; pronotal tubercles punctured. Prosternum in front of coxae 0.6 times shorter than diameter of coxal cavity. Scutellum transverse, more than three times as wide as long. Elytra elongate, 1.4 times as long as wide at widest part, 1.6 times as long as pronotum, widest at middle; each elytron with three rows of tubercles irregular in shape and size (Figs 13,14), tubercles only slightly elevated from deeply wrinkled elytral surface; sparsely covered with large deep punctures arranged in rows, visible mainly from the lateral view. Legs long, slender; with all tibial spurs distinct; right protarsus and metatarsus with only tarsomere I preserved, right mesotarsus missing; relative lengths of metatarsomeres 1.0 : 0.8 : 1.2 : 1.8.
Male genitalia with tegmen elongate, widest before middle, basally with short strut; parameres elongate, less than half of phallobase length, with dense long setae at apical half (Fig. 19). Penis weakly curved at lateral view, apically truncate; dorsal struts diverged from about 1/2 of penis length. Internal sac long, with paired small medial and distinct flagellar sclerites .
Variability in males. BL 9.4-11.8 mm, BW 3.5-4.3 mm. Antennae 1.0-1.3 times longer than body length. Prothorax laterally with one more or less distinct obtuse tooth; pronotal disc slightly to deeply wrinkled; pronotal and elytral tubercles more distinct in other males than holotype. Male from Kinabalu Park (PCJC) large, with pubescence very dense, yellowish brown, and with slightly narrower tegmen.
Etymology. The name Microdolichostyrax gen. n. refers to the smaller size of the specimens belonging to the genus, and to its similarity to Dolichostyrax Aurivillius. Gender: masculine.
Prothorax as long as wide, laterally with one small obtuse tubercle; pronotal disc with pair of tubercles near middle and one median at second half; pronotal tubercles punctured. Prosternum in front of coxae 0.8 times shorter than diameter of coxal cavity. Scutellum transverse, about 3.5 times as wide as long. Elytra elongate, 1.8 times as long as wide at widest part, 2.3 times as long as pronotum, widest near middle; each elytron with three rows of irregular, slightly elevated tubercles (Figs 27-28), sparsely covered by large deep punctures irregularly in rows, surface not wrinkled. Legs long, slender; relative lengths of metatarsomeres 1.0 : 0.6 : 1:0 : 1.6.
Distribution. Malaysia: Borneo (Sabah: Sipitang, Trus Madi). Etymology. The specific name is a patronym in honor of Mr. Daniel J. Heffern (Houston, USA), who kindly provided us with the type material. Description of holotype (female). BL 9.0 mm, BW 2.9 mm. Body brown; antennae, legs and palpi lighter. Body densely clothed with very short yellowish brown pubescence, incorporating fine detritus particles (Fig. 34).
Prothorax 0.9 times as long as wide, widest at middle, laterally with one small obtuse tubercle; pronotal disc with pair of tubercles near middle and one median at second half; pronotal tubercles punctured. Prosternum in front of coxae 0.9 times shorter than diameter of coxal cavity. Scutellum transverse, about three times as wide as long. Elytra elongate, 1.8 times as long as wide at widest part, 2.3 times as long as pronotum, widest near middle; each elytron with three rows of irregular, slightly elevated tubercles (Figs 34-35), sparsely covered by large deep punctures irregularly in rows; surface not wrinkled. Legs long, slender; relative lengths of metatarsomeres 1.0 : 0.6 : 1:0 : 1.7.
Distribution. Malaysia: Borneo (Sabah: Kuamut). Etymology. The name "minutus" refers to the smaller size of the species.
Description. Body robust, elongate, 10.8 mm long and 3.9 mm wide in male, and 12.6-14.6 mm long and 4.9-5.5 mm wide in females. Body reddish brown to dark brown; appendage joints lighter, palpi brown to black. Body very densely clothed with very short golden brown pubescence; scape, legs, scutellum, apex of elytra and abdominal ventrites covered with longer sparse semi-erected yellow setae (Fig. 47).
Prothorax sub-cylindrical, as long as wide, widest at middle, laterally with one small obtuse tubercle; pronotal disc weakly convex, sparsely covered with deep puncturation, with pair of more or less distinct tubercles near middle and two median at first and second half, respectively; pronotal tubercles smooth or sparsely punctured; anterior and posterior angles obtuse. Prosternum in front of coxae 0.7 times shorter than diameter of coxal cavity, sparsely punctured; procoxal cavities circular, narrowly separated (Fig. 49). Scutellum transverse, about three times as wide as long. Elytra elongate, 1.6-1.7 times as long as wide at widest part, 2.1-2.5 times as long as pronotum, basally wider than posterior pronotal margin, widest slightly after middle, then gradually tapered towards apex, fused along the elytral suture; each elytron with three rows of prominent irregular tubercles forming distinct ridges (Figs 47-48), sparsely covered with large deep punctures located irregularly in rows; elytra covered with very dense short pubsecence, apically with sparse long erected yellowish brown setae; outer elytral margin curved at lateral view (Fig. 48). Mesoventrite with anterior edge on different plane than metaventrite. Both mesoventrite and metaventrite without puncturation. Mesocoxal cavities circular, separated wider than in procoxal cavities. Metaventrite transverse, more than two times wider than long, posterior margin emarginated, with short narrow median emargination. Metacoxal cavities separated slightly wider than in mesocoxal ones, extending laterally to meet elytra (Fig. 49). Hind wing absent. Legs long, slender; femora weakly swollen distally, tibial spurs 0-0-2 in male, 2-2-2 in females, protibiae with pubescent groove (antennal cleaner) on inner face, inner face apically prolonged forming distinct, wide, gradually tapered protrusion in male (Fig.  54), simple in females; mesotibiae with pubescent groove on outer face, inner face with distinct protrusion as in protibiae but shorter in male, simple in female; metatibiae without groove, without protrusion; tarsal formula 4-4-4, relative lengths of metatarsomeres 1.0 : 0.5-0.6 : 0.8-0.9 : 1.2-1.7; last tarsomere with four long erected setae at ventral face, claws simple, empodium absent.
Etymology. The name Borneostyrax is a combination of words "Borneo" (geographical origin of the genus) and "styrax" (part of the generic name Dolichostyrax). Gender: masculine. Description of holotype (male). BL 10.8 mm, BW 3.9 mm. Body dark brown; appendage joints lighter, palpi black. Body very densely clothed with very short golden brown pubescence; scape, legs, scutellum, apex of elytra and abdominal ventrites covered with longer sparse semi-erected yellow setae (Fig. 47).
Prothorax sub-cylindrical, as long as wide, widest at middle, laterally with one small obtuse tubercle; pronotal disc weakly convex, sparsely covered with deep puncturation, with pair of distinct tubercles near middle and two median at first and second half, respectively; pronotal tubercles sparsely punctured; anterior and posterior angles obtuse. Scutellum transverse, about three times as wide as long. Elytra elongate, 1.7 times as long as wide at widest part, 2.1 times as long as pronotum; each elytron with three rows of prominent irregular tubercles forming distinct ridges , sparsely covered with large deep punctures located irregularly in rows; elytra covered with very dense short pubsecence, apically with sparse long erected yellowish brown setae; outer elytral margin curved at lateral view (Fig. 48). Legs long, slender; femora weakly swollen distally, tibial spurs 0-0-2, tarsal formula 4-4-4, relative lengths of metatarsomeres 1.0 : 0.5 : 0.8 : 1.4. Abdomen with five ventrites; first ventrite (excluding intercoxal process) about 1.5 times longer than second; intercoxal process short, broadly rounded. Fifth ventrite with apex broadly rounded, margin with very sparse semi-erect pubescence. Male genitalia with tegmen elongate, widest at posterior 1/3, basally with long strut; parameres short, distinctly shorter than phallobase, apically with short fine setae (Figs 57-58). Penis weakly curved at lateral view, apically acuminate; dorsal struts diverged before 1/2 of penis length. Internal sac moderately long, with paired short medial and distinct flagellar sclerites (Figs 55-56).
Remark. Two females contained large larvae (two and three, respectively) inside their abdomens. The larvae filled most of the females' abdomens and were located with their heads oriented towards the abdominal base (Fig. 64). Apparently, there were thin egg shells at least partly covering the larvae, but unfortunately, we were not able to specify where exactly in internal genitalia were larvae localized due to the partly damaged thin membranous structures inside the female internal reproductive organs. This damage was caused by the dissection because of two factors -first, the presence of larvae in the female abdomen was an unexpected finding as (ovo)viviparity has not been reported for any long-horned beetle to date, and second, it was studied in dry material, re-moistened only before the dissection.

Diversity of Morimopsini in Borneo
Borneo is one of the major biodiversity hotspots in the world (de Bruyn et al. 2014) and especially mountain ranges of north-eastern Borneo, which is the presumed Pleistocene rainforest refugium, host numbers of endemic organisms (e.g. Gathorne-Hardy et al. 2002, Merckx et al. 2015. This is also the case for the flightless Bornean longhorned beetle genera classified in Morimopsini (Breuning 1950), which are distributed almost exclusively in the mountain regions of Sabah, where the endemism appears to be highest (Gathorne-Hardy et al. 2002). This is, however, challenged by some recent studies, which pointed out that the northern parts of the island are just incomparably better sampled than the interior Borneo (see Beck and Rüdlinger 2014 for a review). Therefore, it is not clear whether the current northern distribution of Morimopsini in Borneo is caused by an influence of the Pleistocene refugial history or fact, that no material is known from the Indonesian part of the island which is hardly accessible to scientific exploration. The cerambycid tribe Morimopsini contains many morphologically distinct lineages, and its limits and classification are in deep need of revision (Breuning 1950, Sudre 1997. Because the higher lamiine classification is beyond the scope of this paper, we retain using the Breuning's (1950) concept of the tribe with the inclusion of the Bornean genera Dolichostyrax, Anexodus, and Pantilema. The specimens of Morimopsini are rarely collected, probably due to their cryptic life in the tropical forest litter and highly restricted vagility caused by the absence of wings. Therefore, we had only a limited number of specimens available for our study, but in spite of it, our study revealed that this group is much more speciose than previously believed. We found surprisingly high morphological diversity in the Bornean Morimopsini, which resulted in the descriptions of three new genera with four new species. Given their limited distributional ranges in stable long-term habitats of humid mountain forests together with the high speciation rates known for the flightless lineages (Ikeda et al. 2012, Vogler andTimmermans 2012), the high diversity found in the studied genera is not such surprising. Considering the rarity of Morimopsini specimens in the collections, their life-history and hitherto unexplored areas in Borneo, we can expect many more species will be discovered in that island in the near future.

First case of (ovo)viviparity in Cerambycidae
The vast majority of insects are oviparous, i.e. their females lay eggs and embryogenesis occurs after oviposition. Ovoviviparous species retain their eggs in the genital tracts until the larvae are ready to hatch. There are no special nutritional adaptations developed in egg or female's body; embryo uses only nutritional reserves from the egg cytoplasm. On the other hand, in truly viviparous species the embryo receives nourishment also (or only) from the parent. The ovoviviparity is sometimes considered as a transitional stage between oviparity and viviparity, but also very often treated as a special case of viviparity (Hagan 1951, Iwan 2000, Gullan and Cranston 2014. The (ovo)viviparous reproduction is a relatively rare phenomenon in insects and occurs in some Ephemeroptera, Dermaptera, Blattodea, Plecoptera, Psocodea, Thysanoptera, Homoptera, Neuroptera, Coleoptera, Strepsiptera, Hymenoptera, Diptera, Trichoptera and Lepidoptera (e.g. Hagan 1951, Michaelis 1984, Meier et al. 1999, Iwan 2000, Heppner 2009, Kočárek 2009). However, the reproductive strategies of many insect lineages remain unknown, and the viviparity might be in fact much more common.
Within Coleoptera, viviparity (in all cases as ovoviviparity) has been reported only for the several phylogenetically unrelated families -adephagan Carabidae (Liebherr and Kavanaugh 1985) and polyphagan Staphylinidae (Aleocharinae; Schiødte 1853), Chrysomelidae (Chrysomelinae: Chrysomelini; Perroud 1855, Bontems 1984, Micromalthidae (Barber 1913), and Tenebrionidae (Tenebrioninae: Pedinini and Ulomini; Tschinkel 1978, Iwan 2000, Dutrillaux et al. 2010). Here we add also Cerambycidae to the list of beetle families for which some (ovo)viviparous species are known. In Chrysomelidae, which are phylogenetically related to Cerambycidae (see e.g. McKenna et al. 2015), ovoviviparous females are characterized by the loss of spermatheca and the first instar larvae by the loss of eggbursters (Reid 2014). Another morphological feature associated with ovoviviparity is shortened ovipositor, which is more adapted to laying large eggs or to larviposition (Meier et al. 1999, Iwan 2000. Indeed, the females of Borneostyrax gen. n. have genitalia with short, wide ovipositor and without spermatheca (Fig. 63). In two females out of four, we found relatively large larvae (two and three, respectively) without any visible eggbursters (Fig. 65). These morphological features, which are present exclusively in this genus, clearly indicate the presence of (ovo)viviparity in Borneostyrax gen. n. This phenomenon is commonly associated with parthenogenesis in Chrysomelidae; however, we have a male associated with females in Borneostyrax gen. n. and absolutely no information on the life-history for this lineage. Further detailed study of more material is needed for the better understanding of the reproductive strategy in this genus.