Orthomorpha gladiata, 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 : 12-16

Orthomorpha gladiata sp. n. Figs 10-12

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 emphasize the sword-shaped tip of the gonopod; adjective.

Diagnosis.

Orthomorpha gladiata sp. n. seems to be especially similar to Orthomorpha hydrobiologica Attems, 1930, a species known to range from eastern Java, Indonesia to Indochina ( Likhitrakarn et al. 2011), but differs clearly in the tip of the solenophore being nearly monodentate and sword-shaped.

Description.

Length 25-27 mm (♂), width of midbody pro- and metazona 1.7-1.9 and 2.8-2.9 mm, respectively.

Coloration in alcohol, after one month of preservation, dark brown (Fig. 10 A–G), paraterga and epiproct light yellow or pale yellowish, head, surface below paraterga and antennae brownish, venter and legs whitish to pale brown (Fig. 10 A–I).

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

Antennae (Fig. 10A) reaching body segment 3 when stretched dorsally. In width, head <collum <segments 3 and 4 <2 = 5-16, gently and gradually tapering thereafter. Collum with three transverse rows of setae: 3+3 in anterior, 2+2 in intermediate, and 3+3 in posterior row; caudal corner of paraterga very narrowly rounded, slightly upturned, but not drawn behind rear margin (Fig. 10A, B).

Postcollum metaterga with two transverse rows of setae traceable at least as insertion points when setae broken off: 2+2 in anterior (pre-sulcus) and 3+3 in posterior (post-sulcus) row, these setae being borne on small cones growing stronger laterally. Metaterga 17-19 with 4+4 setae in posterior row, likewise borne on evident cones growing stronger laterally. Axial line rather difficult to see, but traceable both on pro- and metaterga. Paraterga very strongly developed (Fig. 10 A–G), mostly slightly upturned, all lying faintly below dorsum, set at about upper 1/4 of midbody height, mostly subhorizontal, caudal corner narrowly rounded to nearly pointed; paraterga very thin in lateral view, modestly enlarged in pore-bearing segments, thinner in poreless ones. Calluses on paraterga 2-4 delimited by a sulcus only dorsally, on following paraterga both dorsally and ventrally. Paraterga 2 broad, anterior edge rounded, lateral edge with one larger and one smaller, but evident incision in anterior 1/3; posterior edge clearly concave (Fig. 10A, C, F). Anterior edges of paraterga broadly rounded and narrowly bordered, fused to callus. Lateral edge of paraterga with two slight, but evident incisions, one in anterior 1/3, the other in posterior 1/3. Posterior edge of paraterga clearly concave, lateral corner extending increasingly beyond rear tergal margin, especially strongly so in segments 17-19 (Fig. 10F, G). Transverse sulcus usually distinct (Fig. 10A, C, F), complete on metaterga 5-18, incomplete in segments 4 and 19, rather deep, reaching bases of paraterga, rather clearly ribbed at bottom. Stricture between pro- and metazona narrow, clearly ribbed at bottom down to base of paraterga (Fig. 10 A–F). Pleurosternal carinae complete crests with a sharp caudal tooth in segments 2-4, a very sharp, caudal tooth in segments 5-7, a small, mostly sharp tooth until segment 16 (Fig. 10B, D, E). Epiproct (Fig. 10F, G) conical, flattened dorsoventrally, with two evident apical papillae; tip subtruncate; pre-apical papillae small, but visible, lying rather close to tip.

Two small, low, rounded, fully separated, sternal cones between ♂ coxae 4 (Fig. 10H, I). A paramedian pair of evident tubercles in front of gonopod aperture. Legs rather long and slender, midbody ones ca 1.2-1.4 times as long as body height, prefemora without modifications, ♂ tarsal brushes present only on legs 1-3.

Gonopods (Figs 11, 12) with slender and long coxae, the latter with several setae distoventrally. Femorite about 3 times as long as prefemoral portion. Femorite very slender, slightly curved, postfemoral portion demarcated by an oblique lateral sulcus. Solenophore with a nearly monodentate and sword-shaped tip; solenomere long and flagelliform.

Remarks.

The gonopod tip of Orthomorpha gladiata sp. n. is much like in Orthomorpha parasericata Likhitrakarn, Golovatch & Panha, 2010, from southern Thailand ( Likhitrakarn et al. 2010, 2011), but the new species differs clearly not only in some somatic characters (e.g. the considerably broader paraterga), but also by the presence of an evident oblique sulcus demarcating a gonopod postfemoral portion.