(Figs. 1, 2, 3, 4, 5, 6, 7, 12, 18, 24, 27, 44, 50, 56, 62, 66, 72, 76)
Devadatta species B;— Dow & Ngiam 2014: 9, 42, 44 (Ulu Balui, Ulu Baleh);— Dow et al. 2015 a: 8, 22 (Batang Ai National Park and Kapit).
Devadatta spp. cf podolestoides;— Dow & Ngiam 2012: 2, 7 (Hose mountains: part).
Type material. Holotype: 1 ♂ (SAR 13 _ 14 _ DEV 99), stream in virgin forest, Sungai Kahei area, Ulu Balui, Kapit division, 10 ix 2013, leg. R.A. Dow, to be deposited in RMNH.
Paratypes (189 ♂ 27 ♀). Female used for description: 1 ♀ (SAR 13 _ 14 _ DEV 100, in tandem with holotype), data as holotype See appendix for remainder.
Etymology. Somoh, a noun in apposition, named for Somoh anak Nyapong, friend of the first author and an essential figure on many of the trips during which material of this species has been collected.
Diagnosis. A typical member of the podolestoides -group. In most known populations males can be distinguished from those of other species by the darker occipital area of the head and venter of the synthorax, females by the long, upward and rearward directed horns on the middle pronotal lobe. Additionally males can be separated from those of D. clavicauda by the less expanded ends of the cerci in D. somoh, females by the presence of pronotal horns in D. somoh.
Description of holotype male. Head: Labium mostly pale. Mandible bases and genae mostly shining dark brown. Labrum, clypeus, frons and vertex to level of lateral ocelli black with metallic green reflection, antennae mostly dark brown and black. Remainder of dorsum of head matte black with small, indistinct brown areas on protruding postocular lobes, not joined (Fig. 18), underside extensively pale.
Thorax: Pronotum and propleuron largely black, with pale streak below notopleural suture, small pale marks laterally on anterior pronotal lobe, rear of middle pronotal lobe brown. Dorsum of synthorax matte black, pale diamond-shaped mark between arms of anterior bifurcation of middorsal carina. Synthorax laterally mostly matte black, with pale marks as follows (Fig. 24): along lower side of mesopleural suture short faint streak and small faint patch near antealar carina, faint brown mark around interpleural suture adjacent to posterior coxa, narrowly separated from bright streak above spiracle, becoming thinner and fainter towards antealar carina, small bluish subtriangular area below metapleural suture adjacent to antealar carina, indistinct, larger, faint brown area at other end metapleural suture. Area between metapleural carina and venter dark brown. Venter of synthorax centrally pale, dark brown laterally and on meteposternum (Fig. 27). Legs: Coxae largely dark brown. Trochanters pale with dark marks on extensor surface. Femora, tibiae and tarsi brown. Wings with arculus ca at level of Ax 4, quadrilateral with 2 crossveins, cubito-anal space free in all wings, pt dark brown. Membrane with slight brownish tint, darker at extreme tips of Fw.
Abdomen: Black above and very dark brown laterally, becoming almost entirely black on terminal 3 segments, S 3–8 with broad pale basal ring, brown and faint dorsally, smallest on S 8. Genital ligula typical for the group, seminal vesicle brown. Cerci black, paraprocts brown, paler above. Paraprocts extremely short, rounded. Cerci longer than S 10, in dorsal view (Fig. 44) broad at base, narrowing to ca one-half of their length from base, where in-turned at ca a right angle, apical half slightly expanded. In lateral view (Fig. 50) slender after base, of constant width until apex, slightly upturned towards apex. Interiorly deeply excavated from shortly after base, this excavation running almost to apex, pale inside excavation.
Measurements (mm): Abdomen without anal appendages 34.5, cerci ca 1, Hw 30.
Description of female (SAR 13 _ 14 _ DEV 100). As male except as noted. Head. Labrum mostly brown. Most of mandible bases, frons and postclypeus brown, remainder of dorsum of head matte black with postocular lobes brown, joined by pale band along occipital ridge (Fig. 56). Antennae with anterior yellow streak on scape.
Thorax: Propleuron with extensive whitish pruinosity. Pronotum (Fig. 62, 66) mottled brown, larger pale marks on anterior lobe, middle lobe bearing long finger-like horns, directed upward, slightly inward, and rearward over anterior half of posterior lobe. Dorsum of synthorax brown with middorsal carina black, small pale mark between arms of anterior bifurcation of middorsal carina. Synthorax laterally brown with pale marks brighter than in male (Fig. 72), more extensive, nearly continuous pale mark along interpleural suture. Venter of synthorax largely brown with only small central paler area. Wings with arculus at Ax 3 in left Hw, quadrilateral with one crossvein in Fw, pt black proximally apical ca 2 / 3 mostly pale. Extreme tips of both wings brown, darker in Hw.
Abdomen: Small pale lateral basal spot on S 2, basal ring almost absent on S 8. Cerci black, subtriangular, ca same length as S 10. Ovipositor short, only reaching beyond S 10 to ca level of tips of cerci.
Measurements [mm]: Abdomen without ovipositor and appendages 29, Hw 27.5.
Variation in paratypes. Males: Apart from small differences in size and shape of pale markings on thorax and abdomen there is little variation. Some individuals have extensive whitish pruinosity on coxae, trochanters, adjacent parts of synthorax and venter of synthorax. Arculus at level of Ax 3 or 4, pt occasionally with a paler area centrally. In most individuals the extreme tips of both wings are brown, and it is common for most of the wing to have a light brownish tint. Single crossveins are present in the cubito-anal apace of one wing in a few male specimens.
Most males from Batang Ai National Park, and some from Lanjak Entimau Wildlife Sanctuary (the most western locations known for this species) have the venter of the synthorax much more extensively pale, some from Batang Ai resembling D. aran in this respect, and also having larger and brighter pale marks on the synthorax. However, in most of these specimens the area between the metapleural carina and venter of synthorax is brown in D. somoh, in a few cases it is paler than typical and largely greyish. In other populations the venter of the synthorax sometimes comes close to that seen in the D. tanduk paratype shown in Fig. 29; the single specimen from Brunei is in this category.
The cerci frequently appear slightly more expanded towards the apex in lateral view than in the holotype. One individual (SAR 13 _ 14 _ DEV 133) has cerci that appear to have been squashed towards their apices, so that they appear much thinner in dorsal view than typical, and slightly more expanded apically in lateral view than is typical. Another (SAR 13 _ 14 _ DEV 38: RMNH.INS. 509912) has the apical ca half of the cerci turned downwards at nearly a right angle. In both these highly atypical cases we consider the differences to be the result of either malformation or damage (presumably at emergence or while teneral) to the individual. The cerci of all males (including the holotype) bear small spines; these are highly variable in size and position and non-diagnostic.
Females: apart for small variations in markings, the ground colour of the thorax varies from pale to dark brown, arculus at Ax 3–4, the extent of the pale part of pt varies, entirely absent in one individual, and pt entirely pale in another (this variation is associated with maturity), the brown area at the wing tips varies in size and intensity but is always more extensive than in males. One female paratype has a crossvein in the cubito-anal space of one Hw. In the female from Batang Ai the horns on the middle pronotal lobe are directed somewhat inward and only slightly rearward, so they do not overlap the posterior lobe, thus resembling females of D. tanduk.
Measurements [mm]. Males: abdomen without anal appendages 29 –37.5, Hw 25.5–31.5. Females: abdomen without cerci or ovipositor 28 –31.5, Hw 26.5–29.5.
Remarks. Devadatta somoh has a known range almost entirely within Sarawak, covering Kapit division and parts at least of Bintulu, Miri and Sri Aman divisions; just one male has been collected in Brunei. At Batang Ai National Park in Sri Aman division it is the only Devadatta species yet found and in the Nanga Bloh area in southwest Kapit division (part of the Lanjak Entimau Wildlife Sanctuary which is contiguous with Batang Ai) the only other Devadatta species that has been found is D. clavicauda (which appears to be very uncommon there). Across the rest of its range it overlaps with one or both of D. aran and D. clavicauda. In Miri division D. somoh is not common, with just a few records from the mid and upper Baram, and from Gunung Mulu National Park. Given that some records from Kapit division are extremely close to the Indonesian border, it is to be expected in parts of Kalimantan. It is found in small forest streams in hilly and mountainous terrain, from the lowlands up to at least 900m, but, at least where their ranges overlap, D. aran is typically more common at higher altitudes.