Orthomorpha sutchariti, Likhitrakarn, Natdanai, Golovatch, Sergei I. & Panha, Somsak, 2014

Likhitrakarn, Natdanai, Golovatch, Sergei I. & Panha, Somsak, 2014, The millipede genus Orthomorpha Bollman, 1893 in Laos (Diplopoda, Polydesmida, Paradoxosomatidae), with descriptions of new species, ZooKeys 374, pp. 1-22 : 16-19

Orthomorpha sutchariti sp. n. Figs 13-15

Holotype

♂ (CUMZ), Laos, Champasak Province, Paksong District, Tadedu, 906 m a.s.l., 15°11'35"N, 106°06'07"E, 16.10.2013, leg. S. Panha and C. Sutcharit.

Paratype.

1 ♀ (CUMZ), same data, together with holotype.

Name.

To honour Dr. Chirasak Sutcharit, Professor at the Department of Biology of Chulalongorn University, Bangkok, who participated in collecting the type specimens and taught the first author the basics of taxonomy.

Diagnosis.

Differs in the colour pattern which has lighter caudal halves of the metaterga, the mostly strongly elevated and laterally bordered paraterga, and a trifid solenophore showing a subacuminate, longest, dorsal prong.

Description.

Length ca 42 mm (♂) or 44.5 mm (♀), width of midbody pro- and metazona 3.4 and 4.8 mm (♂), 3.5 and 5.6 mm (♀), respectively.

Coloration in alcohol, after one month of preservation, rather uniformly dark brown (Fig. 13 A–G) with lighter caudal halves of metaterga, paraterga and epiproct contrasting light yellow, mid-dorsal regions of prozona strongly infuscate, blackish like most of metaterga; antennae and legs brown to light brown (Fig. 13 A–I).

All other characters as in Orthomorpha paviei , except as follows.

Antennae (Fig. 13A, B) surpassing posterior end of body segment 3 (♂) or 2 (♀) when stretched dorsally. In width, head <collum <segment 3 = 4 <2 <5-15, gently and gradually tapering thereafter. Collum with three transverse rows of setae: 4+4 in anterior, 2+2 in intermediate, and 4+4 in posterior row; a very faint incision laterally near midway; caudal corner of paraterga very narrowly rounded, slightly upturned, but not drawn behind rear margin (Fig. 13A, B).

Tegument smooth and shining, metaterga smooth and delicately rugulose, leathery, posterior halves of metaterga rugose, with traces of tubercles/wrinkles; surface below paraterga finely microgranulate. Postcollum metaterga with two transverse rows of setae traceable at least as insertion points when setae broken off: 2+2 in anterior (pre-sulcus), 3+3 in posterior (post-sulcus) row. Axial line faint, but traceable both on pro- and metaterga. Paraterga very strongly developed (Fig. 13 A–G), mostly slightly upturned, lying either faintly above (♂) or slightly below dorsum (♀), set at about upper 1/3 of midbody height, subhorizontal (♀), caudal corner very narrowly rounded, extended beyond rear tergal margin, increasingly well produced caudally in segments 16-19 (Fig. 13F, G); paraterga very thin in lateral view, blunt blades, modestly enlarged in pore-bearing segments, thinner in poreless ones. Calluses on paraterga 2 and 3 delimited by a sulcus only dorsally, on following paraterga both dorsally and ventrally. Paraterga 2 broad, anterior edge angular, lateral edge with one stronger and two smaller, but evident incisions in anterior 1/3; posterior edge clearly oblique (Fig. 13A, C, F). Anterior edges of paraterga broadly rounded and narrowly bordered, fused to callus. Transverse sulcus usually distinct (Fig. 13A, C, F), complete on metaterga 5-18, incomplete and nearly wanting on segments 4 and 19, shallow, not reaching bases of paraterga, rather faintly ribbed at bottom. Stricture between pro- and metazona narrow, clearly ribbed at bottom down to base of paraterga (Fig. 13 A–F). Pleurosternal carinae complete crests with a sharp caudal tooth in segments 2-7 (♂) or 2-4 (♀), a very sharp, caudal tooth in segments 8-15 (♂) or 5-10 (♀), a small, mostly sharp tooth until segments 16-19 (♂) or 11-17 (♀) (Fig. 13B, D, E). Epiproct (Fig. 13F, G) conical, flattened dorsoventrally, with two evident apical papillae, both directed ventrocaudally and acute at tip; pre-apical papillae small, lying rather close to tip.

A pair of small, rounded, fully separated, sternal cones between ♂ coxae 4 (Fig. 13H, I). A paramedian pair of evident tubercles in front of gonopod aperture. Legs rather long and slender, faintly incrassate in ♂; midbody legs ca 1.2-1.4 (♂) or 0.9-1.1 (♀) times as long as body height, prefemora without modifications, ♂ tarsal brushes present until legs of segment 8.

Gonopods (Figs 14, 15) with slender and long coxae, the latter with several setae distoventrally. Femorite about 3 times as long as prefemoral portion. Femorite slender, slightly curved, postfemoral portion demarcated by an oblique lateral sulcus; tip of solenophore trifid, with dorsal lobule being subacuminate and longest, middle denticle spiniform, shortest; solenomere long and flagelliform.

Remarks.

The colour pattern of Orthomorpha sutchariti sp. n. is similar to that observed in several species of the Oriental genus Antheromorpha Jeekel, 1968 (our personal observations), but the gonopod structure is typical of Orthomorpha spp. Due to the particularly short middle prong at the tip of the solenophore, this new species strongly resembles the numerous congeners within the former weberi-group ( Likhitrakarn et al. 2011).