Orthomorpha rotundicollis (Attems, 1937)

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 : 49-54

Orthomorpha rotundicollis (Attems, 1937) Figs 4346

Pratinus rotundicollis Attems 1937: 118 (D).

Pratinus rotundicollis - Attems 1938: 217 (D); 1953: 170 (R).

Pratinus tuberculatus Attems 1937: 119 (D), syn. n.

Pratinus tuberculatus - Attems 1938: 219 (D).

Orthomorpha rotundicollis - Jeekel 1963: 265 (M); 1964: 361 (M, D); 1968: 56 (M); Hoffman 1973: 363 (M); 1977: 700 (M); Golovatch 1998: 42 (M, D); Enghoff et al. 2004: 38 (M, R).

Orthomorpha tuberculata - Jeekel 1963: 265 (M); 1964: 361 (M, D); 1968: 56 (M); Hoffman 1977: 700 (M); Golovatch 1998: 42 (M, D); Enghoff et al. 2004: 39 (M, R).

Lectotype.

♂ of Pratinus rotundicollis (NHMW-3515), Vietnam, Lamdong Prov., Lang Biang, Arbre-Broyé, 1500 m, 01.02.1931, leg. C. Dawydoff.

Paralectotype.

1 ♂ of Pratinus rotundicollis (NHMW-3515), Vietnam, Lamdong Prov., Dalat, 1500 m, 02.1933, leg. C. Dawydoff.

Non-type material.

1 ♀ of Pratinus rotundicollis (NHMW-8000), Laos, Xiangkhoang Prov., Xiangkhoang Plateau, Xiang Kuang, no date, leg. C. Dawydoff, det. Attems.

Syntypes.

2 ♂, 1 ♀, 1 juv. of Pratinus tuberculatus (NHMW-3519), Vietnam, Lamdong Prov., Peak Lang Biang, Arbre-Broyé, 1500 m, 01.02.1931, leg. C. Dawydoff.

Lectotype designation proposed herewith is necessary to ensure the species is based on a complete male coming from a certain locality, because (1) ( Attems (1937, 1938) had provided no information on the number of syntypes, and (2) he stated their provenance to have been both from Arbre-Broyé and Dalat, Vietnam.

Redescription.

Length 29-31 mm (♂), ca 31-35 mm (♀), width of midbody pro- and metazona 2.5-3.0 and 3.7-4.1 mm (♂), 3.4 and 4.5 mm (♀), respectively (vs 2.5 and 4.0 mm in width, as given in the available descriptions ( Attems 1937, 1938)). Lectotype ca 31 mm long, 2.9 and 4.1 mm wide on midbody pro- and metazona, respectively. Coloration of alcohol material upon long-term preservation rather uniformly light grey-brown (Figs 43 & 45) (vs with a cingulate pattern of castaneous brown head and collum, as well as regions of pro- and metazona adjacent to stricture alternating with light brownish remaining parts, including antennae and legs, as given in the descriptions ( Attems 1937, 1938)).

Head usual, clypeolabral region densely setose, surface of vertex smooth, epicranial suture distinct. Antennae rather long and slender (Figs 43J, 45B & J), extending behind body segment 4 (♂) or 3 (♀) dorsally. Head in width <collum <segments 3 and 4 <segment 2 <segments 5-17 (♂, ♀), gently and gradually tapering thereafter. Collum smooth, with three transverse rows of setae, 4+4 anterior, 2+2 intermediate, and 3+3 posterior setae; caudal corner of paraterga subrectangular, narrowly rounded (Figs 43A, B, J, 45A, B & J). Tegument smooth and shining; metaterga very faintly rugulose, each postcollum one with one caudal row of 3(4)+3(4) very small tubercles growing a little larger laterally, as well as with 2+2 either minute or fully obliterated knobs with insertion points of abraded setae in front row; prozona very finely shagreened, surface below paraterga finely microgranulate. Axial line visible, starting from collum. Paraterga very strongly developed (Figs 43A-G, J-L, 45A-G & J-L), all subhorizontal and lying below dorsum, thin in lateral view, like blunt blades, a little thicker only on pore-bearing segments, on postcollum segments extending increasingly beyond rear tergal margin, nearly pointed to pointed, caudal tip on paraterga 16-19 evidently curved mesad. Calluses on delimited by a sulcus only dorsally, rather narrow. Paraterga 2 broad, anterior edge angulate, lateral edge with three small incisions in anterior half; posterior edge evidently concave (Figs 43A, B, J, 45A, B & J). Paraterga 3 and 4 subequal, like subsequent paraterga, anterior edge broadly rounded, bordered and fused to callus, lateral edge with two small incisions in anterior half on poreless segments, with only one incision near front 1/3 on pore-bearing ones. Ozopores evident, lateral, lying inside an ovoid groove at about 1/4 metazonital length. Transverse sulcus complete on metaterga 5-18, incomplete on metatergum 4, shallow, not reaching bases of paraterga, beaded at bottom, slightly sinuate anteromedially (Figs 43A- D, F, J-L, 45A-F & J-L). Stricture between pro- and metazona rather narrow, deep, ribbed at bottom down to base of paraterga. Pleurosternal carinae complete crests only on segments 2-4 (Figs 43B, D, E, J-K, 45A-F & J-L), each with an evident sharp denticle caudally, thereafter increasingly strongly reduced until segment 10 (♂, ♀). Epiproct (Figs 43E-G, 45E-G) conical, flattened dorsoventrally, apical papillae small; tip subtruncate; pre-apical papillae small, but visible, lying close to tip. Hypoproct (Figs 43G, 45G) roundly subtriangular, setiferous knobs at caudal margin small and well-separated.

Sterna sparsely setose, without modifications, but with two rather large, rounded, fully separated, but nearly contiguous, setose cones between ♂ coxae 4 (Figs 43H, I, 45H & I). A paramedian pair of small tubercles in front of gonopod aperture. Legs long and slender, midbody ones ca 1.2-1.3 (♂) or 0.8-0.9 (♀) as long as midbody height, prefemora without modifications, tarsal brushes present until ♂ legs 4.

Gonopods (Figs 44 & 46) simple. Coxa long and slender, with several setae distodorsally. Prefemur densely setose, nearly 3 times shorter than femorite + “postfemoral” part. Femorite very slender, evidently curved, very slightly enlarged distad, “postfemoral” part demarcated by an oblique lateral sulcus; tip of solenophore small, trifid, with two subequal denticles (one terminal, the other middle) and a broader subterminal lobule.

Remark.

This species is known from Lamdong Province, southern Vietnam and Luang Prabang Province, Laos ( Attems 1938, 1953). The type locality of both Orthomorpha rotundicollis and Orthomorpha tuberculata being exactly the same ( Arbre-Broyé at Peak Lang Biang), and the differences between them so minor, rather to be treated as infraspecific variations, we are inclined to formally synonymize these species. Indeed, distinctions are observed only in Orthomorpha rotundicollis showing a slightly more rounded caudal corner of the paraterga on the collum (vs slightly more angular in Orthomorpha tuberculata ), in the front row of metatergal setae (= insertion points) borne on virtually fully obliterated knobs (vs on minute knobs in Orthomorpha tuberculata ), and in the apical papillae on the epiproct directed more caudally than ventrally (vs more ventrally than caudally in Orthomorpha tuberculata ) ( Attems 1937, 1938, 1953). We can also add another two differences: paraterga 18 and 19 seem to be a little shorter in Orthomorpha rotundicollis than in Orthomorpha tuberculata , and the caudal row of tubercles on a few caudalmost metaterga demonstrating a pattern of 3+4 or 4+3 in Orthomorpha tuberculata (vs invariably 3+3 in Orthomorpha rotundicollis ).

The above is a combined redescription, based on material of both nominate species.