Orthomorpha sericata Jeekel, 1964

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 : 38-42

Orthomorpha sericata Jeekel, 1964

Figs 14 & 15 .

Orthomorpha sericata Jeekel, 1964: 355 . Orthomorpha sericata: Enghoff, 2005: 98 .

Material examined: Paratypes: 2 males, 1 female ( ZMUC), Thailand, Wat Sum, Bandon River, 7 January 1935. leg. G. Seidenfaden.

NB: This locality is in doubt, in fact most probably referring to Thailand, Surat Thani Province, Kanchanadit District, near Bandon River, Wat Son (Son Temple).

Diagnosis: Differs from congeners in only the caudal parts of the paraterga being contrastingly light, coupled with only slightly dull metaterga and the subtruncate tip of the solenophore.

Redescription: Length about 27 (male) to 30 mm (female), width of midbody pro- and metazona 2.0 and 2.5–3.2 mm (male), 2.5 and 3.3–3.5 mm (female), respectively. Coloration of alcohol material after long-term preservation uniformly castaneous with contrastingly whitish to yellow caudal parts of paraterga and tip of epiproct ( Figs 14 A–G, J–L).

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

Vertigial part generally smooth and shining, only very faintly rugulose; a pair of evident, but not lighter oblong knobs above antennal sockets; epicranial suture very distinct. Head in width <collum <segments 3 and 4 <2 <5–16 (male), or head = collum = segments 3 and 4 <2 <5–16 (female), gradually tapering thereafter. Collum slightly shining, with three rows of setae, 4+4, 2+2 and 3+3; paraterga like small, very regularly rounded and declined flaps.

Tegument generally smooth, but dull ( Figs 14 A–G, J–L), at places rugose to rugulose, only calluses and ventral surfaces of paraterga, as well as surface below paraterga and venter slightly shining. Prozona and metaterga delicately shagreened, metaterga with two rows of extremely faint, setigerous knobs often shown as lighter insertion points: 2+ 2 in fore row, 3+3 near rear margin. Surface below paraterga 2 and 3 more roughly shagreened and even rugose. Paraterga not so strongly developed ( Figs 14 A–G, J–L), mostly upturned, set high, but remaining below dorsum on segments 2–4 and 19, lying slightly above dorsum on segments 5–18, caudal tip almost to fully pointed. Paraterga 2 with one small, but evident denticle anterolaterally, subsequent paraterga with only one faint incision in about anterior 1/3 of lateral extent ( Figs 14 A, C, E, J & L). Paraterga 2–19 with anterior edge clearly convex, at least slightly surpassing rear contour; caudal edge nearly straight to evidently concave, narrowly bordered, slightly fringed near base, but devoid of lobe. Stricture between pro- and metazona shallow, narrow, striolate down to slightly below paraterga. Transverse sulcus incomplete, lineshaped (male) or as an impression (female) on metatergum 4, evident, fully developed, but thin, slightly arcuate, line-shaped and reaching bases of paraterga on segments 5–16 (male) or 5–18 (female), as a very faint impression on metaterga 17–19 (male) or 19 (female), never beaded at bottom. Pleurosternal carinae welldeveloped, as complete, arcuate ridges with distinct (male) or small (female) caudal denticle on segments 2–4, as distinct caudal denticle on segments 5–9, as vestigial caudal denticle on segments 10–12 (male), or as vestigial caudal denticle on segments 5–8 (female), entirely absent thereafter. Epiproct with evident apical and small preapical papillae ( Figs 14 E–G). Cones between male coxae 4 fully separated, rounded ( Figs 14 H & I). Ridge in front of gonopod aperture lower than in O. enghoffi sp. n. Legs longer, about 2.0 (male) or 1.6 times (female) as long as midbody height.

Gonopods ( Fig. 15 ) with a subtruncate, distally extended tip of solenophore.

Remarks. Although this species has been described and depicted in detail ( Jeekel, 1964), it seems appropriate to reiterate its main distinctive features here, providing a new description and abundant illustrations in the present revision, based on paratype material. Live animals are very likely to show a more vivid colour pattern, as observed at least in most of the other known congeners from the sericata -group.

Figures

FIGURE 14. Orthomorpha sericata Jeekel, 1964, male (A – I) and female (J – L) paratypes. A & B: anterior part of body, dorsal and lateral views, respectively. C, D, J & K: segments 10 and 11, dorsal, lateral, dorsal and lateral views, respectively. E – G & L: posterior part of body, dorsal, ventral, lateral and dorsal views, respectively. H & I: sternal cones between coxae 4, subcaudal and sublateral views, respectively.

FIGURE 15. Orthomorpha sericata Jeekel, 1964, male paratype. A & B: right gonopod, mesal and lateral views, respectively. C – F: distal part of right gonopod, submesal, lateral, sublateral and suboral views, respectively. Scale bar: 0.1 mm.