Orthomorpha tergoaurantia Likhitrakarn, 2025

Orthomorpha tergoaurantia Likhitrakarn sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Material examined.

Holotype: ♂ ( CUMZ -PD 0031 ), Cambodia, Kampot Province, Banteay Meas District, Prasat Phnom Totong Temple (locality code C 042), ca 50 m a. s. l., 10°41'50"N, 104°31'21"E, 15. 09. 2019, leg. R. Srisonchai. GoogleMaps Paratypes: 2 ♀♀ ( CUMZ -PD 0031 ), same data, together with holotype GoogleMaps . 1 ♂, 1 ♀ ( CUMZ -PD 0032 ), Cambodia, Kampot Province, Tuek Chhou District, Phnom Chhngok Cave Temple (locality code C 046), ca 60 m a. s. l., 10°38'35"N, 104°16'04"E, 16. 09. 2019, leg. R. Srisonchai GoogleMaps ; 2 ♂♂, 1 ♀ ( CUMZ -PD 0033 ), Cambodia, Kampong Speu Province, Samraong Tong District, Khum Skuh , Phnom Cheal Pagoda (locality code C 031), ca 210 m a. s. l., 11°23'12"N, 104°30'35"E, 13. 09. 2019, leg. R. Srisonchai GoogleMaps ; 3 ♂♂ ( CUMZ -PD 034 ), Cambodia, Kampot Province, Krong Kampot District, side of Road no. 33, beside the Preaek Tuek Chhu River (locality code C 049), ca 5 m a. s. l., 10°36'41.2"N, 104°13'23.8"E, 16. 09. 2019, leg. R. Srisonchai GoogleMaps .

Etymology.

The species name ‘ tergoaurantia’ is derived from the Latin words ‘ tergum’, meaning ‘ back’, and ‘ aurantium’, meaning ‘ orange’. This name emphasizes the distinctive dark or bright orange coloration of the paraterga, which is a prominent characteristic distinguishing it from other Cambodian congeners.

Diagnosis.

This new species seems to be particularly similar to Orthomorpha cambodjana ( Attems, 1953) in gonopod conformation, sharing a very slender and suberect gonopodal telopodite. However, it clearly differs by its larger body size ( 35.4–39.4 mm long and 4.1–4.9 mm wide in ♂, 35.4–39.4 mm long and 4.2–4.3 mm wide in ♀, vs 17–30 mm long and 2.0– 3.1 mm wide in ♂, 19–29 mm long and 2.0– 3.4 mm wide in ♀ of O. cambodjana ) and by the shape of the solenophore apex. The caudal denticle on the pleurosternal carinae is traceable until body rings 7 or 8 in the new species ( vs rings 16 or 17 in O. cambodjana ). Additionally, tarsal brushes are present until ♂ legs of ring 17 in the new species, vs only until ♂ legs 7 of O. cambodjana .

Description.

Length 31.2–37.3 mm ( ♂), 35.4–39.4 mm ( ♀), width of midbody pro- and metazona 2.5–3.2 and 4.1–4.9 mm ( ♂) or 3.2–3.9 and 4.7–5.7 mm ( ♀), respectively.

Coloration of live animals dark brown to blackish (Fig. 1 View Figure 1 ), with contrasting dark orange to bright orange or yellowish paraterga and epiproct; antennae black; venter and legs brown to blackish; coloration of alcohol material after six years of preservation faded to dark castaneous brown, paraterga, venter, epiproct, and several basal podomeres more flavous, pale pinkish, brownish or pale yellow (Fig. 2 A – G View Figure 2 ).

Clypeolabral region and vertex sparsely setose, epicranial suture distinct. Antennae long (Fig. 2 B View Figure 2 ), reaching or extending past ring 3 ( ♂) or reaching to ring 3 ( ♀) when stretched dorsally. In width, head <collum <ring 3 <4 <2 <5 <6 <7–16 (Fig. 2 A View Figure 2 ), thereafter body gently and gradually tapering. Collum with three transverse rows of strong setae: 4 + 4 anterior, 2 + 2 intermediate, and 4 + 4 posterior; a small incision laterally in posterior 1 / 3; caudal corner of paraterga pointed, dentiform, paraterga declined ventrad, not drawn past rear margin (Fig. 2 A, B View Figure 2 ).

Tegument smooth and shining, prozona finely shagreened, metaterga smooth and leathery, posterior halves often rugulose, surface below paraterga microgranulate (Fig. 2 A – F View Figure 2 ). Postcollum metaterga with two transverse rows of rather long setae: 2 + 2 in anterior and 3 + 3 in posterior row (Fig. 2 A, C, F View Figure 2 ), the latter also borne on wrinkles and often abraded, but then readily traceable as insertion points. Tergal setae long, strong, slender, about 1 / 3 metatergal length (Fig. 2 A, D – F View Figure 2 ). Axial line visible both on pro- and metazona. Paraterga very strongly developed (Fig. 2 A – F View Figure 2 ), set high (at ca 1 / 4 metazonal height), upturned in ♂, lying below dorsum on rings 2–5 and 17–19, above dorsum on rings 6–16, in ♀ mostly below dorsum, rather thin in lateral view, a little thicker on pore-bearing rings (Fig. 2 B, D, E View Figure 2 ); anterior margin well-developed, mostly regularly rounded and narrowly bordered, fused to callus; caudal corner narrowly rounded, on postcollum rings extending increasingly past rear tergal margin, better so in ♂, nearly pointed to pointed, caudal tip on paraterga 16–19 evidently curved mesad (Fig. 2 E, F View Figure 2 ). Posterior margin of paraterga clearly concave, especially so in rings 15–19. Calluses on paraterga delimited by a sulcus only dorsally. Paraterga 2 broad, lateral margin with three small incisions, the one near caudal corner being particularly small (Fig. 2 A View Figure 2 ). Paraterga 3 and 4 with two small incisions at lateral margin, one at midway, the other at posterior 1 / 3; anterior incision particularly evident. Lateral margins of following paraterga often with a setigerous incision in anterior 1 / 3, being smaller on pore-bearing rings (Fig. 2 C View Figure 2 ). Ozopores evident, lateral, lying in an ovoid groove at about 1 / 3 metatergal length in front of posterior margin of metaterga (Fig. 2 B, D, E View Figure 2 ). Transverse sulcus usually distinct (Fig. 2 A, C, F View Figure 2 ), slightly incomplete on ring 4, complete and clearly visible on metaterga 5–18, narrow, rather deep, reaching the bases of paraterga, arcuate, beaded at bottom. Stricture between pro- and metazona narrow, deep, beaded at bottom down to base of paraterga (Fig. 2 A, C, F View Figure 2 ). Pleurosternal carinae complete crests on rings 2 and 3, a sharp caudal tooth on ring 4, the tooth gradually reduced into small, caudally roughly granulate crests until ring 7 (8), thereafter missing ( ♂, ♀) (Fig. 2 B, D View Figure 2 ).

Epiproct (Fig. 2 E – G View Figure 2 ) conical, flattened dorsoventrally, subtruncate, with two evident apical papillae directed ventrocaudally (Fig. 2 E, G View Figure 2 ); pre-apical papillae small, but evident, lying close to tip. Hypoproct subtriangular (Fig. 2 G View Figure 2 ), 1 + 1 setiferous knobs at caudal edge well-separated and evident.

Sterna sparsely setose, without modifications; cross-impressions rather deep; a paramedian pair of evident, rounded, fully separated, setose cones between ♂ coxae 4 (Fig. 2 H, I View Figure 2 ). A conspicuous ridge in front of gonopod aperture. Legs long and slender, midbody ones ca 1.3–1.5 ( ♂) (Fig. 2 B, F, G View Figure 2 ) or 1.1–1.3 times ( ♀) as long as body height, prefemora without modifications, ♂ tarsal brushes present until legs of ring 17.

Gonopods long, slender and suberect (Figs 3 View Figure 3 , 4 View Figure 4 ). Coxite long and slender, slightly curved caudally, rather densely setose distodorsally (Figs 3 B, C View Figure 3 , 4 A, B View Figure 4 ). Prefemoral part ( pfe) densely setose, as usual, about 1 / 3 as long as acropodite (femoral + postfemoral parts) (Fig. 3 B, C View Figure 3 ). Femoral part ( fe) long and slender, slightly curved and suberect distad, with a postfemoral part demarcated by an oblique lateral sulcus (Figs 3 B View Figure 3 , 4 B View Figure 4 ). Solenophore ( sph) trifid, its terminal lobule longest, middle prong spiniform and shorter than subterminal lobule (Figs 3 View Figure 3 , 4 A, C – F View Figure 4 ); solenomere ( sl) long and flagelliform.