Orthomorpha latiterga, Likhitrakarn, Natdanai, Golovatch, Sergei I. & Panha, Somsak, 2011

Likhitrakarn, Natdanai, Golovatch, Sergei I. & Panha, Somsak, 2011, Revision of the Southeast Asian millipede genus Orthomorpha Bollman, 1893, with the proposal of a new genus (Diplopoda, Polydesmida, Paradoxosomatidae), ZooKeys 131, pp. 1-161 : 35-38

Orthomorpha latiterga sp. n. Figs 3133

Holotype.

♂ (CUMZ), Thailand, Chanthaburi Prov., Pong Nam Ron Distr., Hin Dard Waterfall, ca 260 m, 12°58'19"N, 102°14'21"E, 17.09.2009, leg. C. Sutcharit.

Name.

To emphasize the extremely broad paraterga.

Diagnosis.

Differs in the extremely broad paraterga, coupled with the pleurosternal carinae represented by complete high crests with a sharp caudal tooth on segments 2-7 (♂) etc. (see also Key below).

Description.

Length 31 mm, width of midbody pro- and metazona 3.1 and 5.0 mm, respectively.

Live coloration (Fig. 31A) black-brown with mainly grey-brownish caudal halves of metaterga and bases of paraterga, and contrasting creamy light orange paraterga and epiproct; antennae blackish, legs light brown; coloration of alcohol material after preservation (Fig. 31B-J) rather uniformly dark brown with lighter caudal halves of metaterga and bases of paraterga, and contrasting pallid paraterga, epiproct and tip of antennae, legs brown to light grey-yellow.

Clypeolabral region sparsely setose, vertex bare, epicranial suture distinct. Antennae moderately long (Fig. 31A & C), extending behind body segment 3 dorsally. Head in width <collum <segments 3-4 <5 <2 <6-16; thereafter body gently and gradually tapering. Collum with three transverse rows of setae, 3+3 anterior, 2+2 intermediate and 3+3 posterior; paraterga (Fig. 31B) only slightly declivous, broadly rounded, and narrowly bordered; caudal corner narrowly rounded, slightly declined ventrally, not extending behind tergal margin; posterior quarter of collum slightly rugulose. Tegument of metaterga shining, rugulose-tuberculate, especially on several front metaterga; prozona very finely shagreened, metazona below paraterga faintly rugulose. Metaterga 2-5 with two rows of 2+2 anterior and 3+3 setiferous cones, except segment 3 with 2+1 in anterior row; usually slightly smaller cones in anterior (pre-sulcus) row and more evident ones laterally in posterior row (Fig. 31B & C); thereafter same pattern, but traceable only as insertion points, tuberculation gradually growing obliterate to become nearly wanting from segment 11 on. Tergal setae short, simple, about 1/3 metatergal length. Axial line visible both on pro- and metazona. Paraterga extremely strongly developed (Fig. 31B-H), broad, all lying below dorsum (at about 1/3 body height), mostly subhorizontal, slightly upturned on segments 2-5 and 18-19, in lateral view modestly enlarged on pore-bearing segments, thinner on poreless ones (Fig. 31E); shoulders always present, mostly nearly straight and narrowly bordered, fused to callus; caudal corner of most of paraterga very narrowly rounded, extending increasingly beyond tergal margin, slightly curved mesad on segments 16-19 (Fig. 31F). Calluses delimited by a sulcus only dorsally, segment 2 with three evident incisions at lateral edge, following segments with two lateral incisions, front one being particularly evident. Posterior edge of paraterga evidently concave, especially strongly so on segments 16-19. Ozopores evident, lateral, lying in an ovoid groove at about 1/3 in front of caudal corner. Transverse sulcus evident (Fig. 31B-F & H), narrow, rather shallow and only slightly incomplete on metaterga 2 and 3, complete, smooth at bottom, reaching base of paraterga on metaterga 4-18. Stricture between pro- and metazona narrow and shallow, evidently beaded at bottom down to base of paraterga. Pleurosternal carinae complete high crests with a sharp caudal tooth on segments 2-7, thereafter increasingly well divided into a front bulge and a caudal tooth, both increasingly strongly reduced in size, bulge until segment 14, tooth until segment 17. Epiproct (Fig. 31F-H) conical, flattened dorsoventrally, very faintly narrowed caudad, subtruncate, with two evident apical papillae directed caudally, both pointed at tip; pre-apical papillae very small, lying close to tip. Hypoproct (Fig. 31G) subtrapeziform, caudal margin rounded, setiferous knobs at caudal edge medium-sized and well-separated.

Sterna sparsely setose, without modifications; cross-impressions shallow; lobe between ♂ coxae 4 much like in Orthomorpha atypica sp. n., but cones more acute (Fig. 31I & J). A paramedian pair of small, but evident tubercles in front of gonopod aperture. Legs moderately long and slender, midbody ones ca 1.2-1.3 as long as body height, prefemora without modifications, ♂ tarsal brushes present only on legs 1-5.

Gonopods (Figs 32, 33) much like in Orthomorpha atypica sp. n., but solenophore tip with more distinct apical lobules.

Remarks.

This new species shows the paraterga relatively perhaps among the broadest amongst congeners.