Orthomorpha asticta, Likhitrakarn, Natdanai, Golovatch, Sergei I. & Panha, Somsak, 2010

Likhitrakarn, Natdanai, Golovatch, Sergei I. & Panha, Somsak, 2010, The millipede genus Orthomorpha Bollman, 1893 in Thailand. 1. Revision of the sericata - group, with descriptions of four new species (Diplopoda, Polydesmida, Paradoxosomatidae), Zootaxa 2361, pp. 23-45 : 33-35

Orthomorpha asticta sp. n.

Figs 9 , 10 , 11 A & B.

Material examined: Holotype male ( CUMZ), Malaysia, Perlis Province, Mt Kaki Bukit, 6°38´22˝N, 100°12´18˝E, 28 March 2008, leg. S. Panha and C. Sutcharit. Paratypes: 2 males, 3 females ( CUMZ), 1 male, 1 female ( ZMUC), 1 male, 1 female ( ZMUM), same data as holotype. 1 male, 2 females ( CUMZ), Malaysia, Kedah, Bukit Kayu Hitam, 27 March 2008, leg. S. Panha and C. Sutcharit. 1 male, Thailand, Satun Province, Tarutao National Park, Ao Chak, 6°42´36˝N, 99°38´29˝E, 6 April 2008, leg. P. Pimvichai. 2 males ( CUMZ), Thailand, same park, Ao Talowao, 6°38´22˝N, 99°41´7˝E, 7 April 2008. leg. P. Tongkerd and R. Chanabun, Non-types: 2 males, 2 females ( CUMZ), same data as paratype from Ao Talowao.

Diagnosis: Differs from congeners in the shining tegument, coupled with only small incisions at the lateral edge, a single, albeit deeply emarginate, lamina between male coxae 4, and the tridentate tip of the solenophore.

Name: To emphasize the absence of a light spot/knob above the antennal sockets.

Description: Length ca 19–23 mm (male), 22–26 mm (female), width of midbody pro- and metazona 1.5–1.8 and 2.6–2.9 mm (male), 2.3–2.5 and 3.2–3.5 mm (female). Live coloration ( Fig. 9 A) blackish, paraterga and epiproct contrastingly dark yellow, head and antennae brownish, legs pale brownish; coloration in alcohol faded to black-brown, pale whitish-grey or pale brown, respectively, after one year of preservation.

Main characters as in O. enghoffi sp. n., except as follows.

No marked light spots above antennal sockets. Vertigial part sparsely setose. Collum with 3rd row of setae not borne on knobs; paraterga small, caudally narrowly rounded, obtusangular, only slightly declined flaps ( Fig. 9 C).

Tegument smooth and shining ( Figs 9 A–H), prozona delicately shagreened, metaterga at places faintly rugulose; surface below paraterga nearly smooth, at places often rugulose as well, devoid of crests, finely microgranulate only below paraterga 2. Metaterga with 2+2 setae in an anterior and 3+3 setae in a posterior row, pattern barely traceable as insertion points, especially that of rear row because of tergal setae being mostly abraded. Tergal setae medium-sized, 1/5 as short as metazonum, retained only in anterior row. Paraterga well-developed ( Figs 9 A–H), usually slightly upturned to subhorizontal, all lying well below dorsum. Anterior edge of paraterga 2 straight, of following paraterga increasingly rounded. Lateral edge of paraterga 3–18 usually with a single, slight incision/knob ( Figs 9 B–F), sometimes absent from one or both sides on pore-bearing segments. Caudal edge of paraterga usually bare, only seldom slightly fringed, without traces of a midway lobule. Posterior edge of poreless paraterga more concave. All paraterga behind collum at least very slightly surpassing tergal contour. Ozopores evident, dorsolateral. Transverse sulcus usually very distinct ( Figs 9 B, D & F), incomplete on segments 5, 6 and 18 (not reaching base of paraterga), complete on metaterga 7–17, deep, line-shaped, slightly arcuated, at most faintly beaded at bottom. Stricture between pro- and metazona clearly ribbed down to base of paraterga. Pleurosternal carinae well-developed as complete arcuate ridges with an acute caudal tooth on segments 2–7 ( Fig. 9 C), retained only as small, caudal, mostly rounded tooth on segments 8–14, as vestigial denticle on segments 16 and 17 (male), or as very faint caudal tubercle on segments 14 and 15 (female), entirely absent thereafter. Epiproct ( Figs 9 F–H) with two small apical papillae, faintly concave tip and pair of small, but evident preapical papillae; tip more broadly emarginate. Male legs 1 and 2 with tarsal brushes. Sternal lamina between male coxae 4 deeply emarginated ( Figs 9 I & J).

Gonopods ( Figs 10 , 11 A & B) with tridentate tip of solenophore.

Remarks. In Malaysia, this species was taken from a limestone mountain. The tridentate tip of the solenophore slightly resembles that observed in species of the weberi -group, but the outer denticles/lobes in O. asticta sp. n. are not rounded, but pointed instead, like is the middle denticle.

Figures

FIGURE 9. Orthomorpha asticta sp. n., male paratype from Mt Kaki Bukit. A: habitus, live coloration. B & C: anterior part of body, dorsal and lateral views, respectively. D & E: segments 10 and 11, dorsal and lateral views, respectively. F – H: posterior part of body, dorsal, ventral and lateral views, respectively. I & J: sternal lamina between coxae 4, subcaudal and sublateral views, respectively.

FIGURE 10. Orthomorpha asticta sp. n., male paratype from Mt Kaki Bukit. A & B: right gonopod, mesal and lateral views, respectively. C – F: distal part of right gonopod, mesal, lateral, dorsal and suboral views, respectively. Scale bar: 0.1 mm.

FIGURE 11. Orthomorpha asticta sp. n., male paratype from Mt Kaki Bukit (A & B) and O. parasericata sp. n., holotype (C & D). A – F: right gonopod, mesal, lateral, mesal and lateral views, respectively. Scale bar: 0.5 mm.