Orthomorpha arboricola (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 : 15-17

Orthomorpha arboricola (Attems, 1937) Figs 910

Pratinus arboricola Attems 1937: 120 (D).

Pratinus arboricola - Attems 1938: 222 (D).

Orthomorpha arboricola - Jeekel 1963: 265 (M); 1964: 361 (M, D); 1968: 56 (M); Enghoff et al. 2004: 38 (M); Golovatch 1998: 42 (D).

Lectotype.

♂ (NHMW-3500), Vietnam, Lamdong Prov., Dalat, 1500 m, 31.01.1935, leg. C. Dawydoff.

Paralectotypes.

2 ♂, 1 ♀, 10 juv. (NHMW-3500), same locality, together with lectotype. Numerous fragments (NHMW-3499), Vietnam, Lamdong Prov., Peak Lang Biang, Arbre-Broyé, 1400 m, 02.02.1931, leg. C. Dawydoff.

Lectotype designation proposed herewith is necessary to ensure the species is based on a complete male.

Redescription.

Length 28-31 mm (♂), 34 mm (♀), width of midbody pro- and metazona 2.3-2.8 and 3.8-4.1 mm (♂), 3.4 and 4.6 mm (♀), respectively (vs up to 38 mm length, as given in the original descriptions ( Attems 1937, 1938)). Coloration of alcohol material upon long-term preservation rather uniformly light brown to brown (Fig. 9) (vs light red-brown to dark brown, as given in the original descriptions ( Attems 1937, 1938)).

Head usual, clypeolabral region sparsely setose (vs densely setose, as given in the original descriptions ( Attems 1937, 1938)), surface of vertex smooth; epicranial suture distinct, flanked by rugulose patches. Antennae long and slender (Fig. 9A), extending behind until body segment 4 (♂, ♀) dorsally. Head in width <collum <segments 3 and 4 <segment 2 <segments 5-16, gently and gradually tapering thereafter. Collum with three transverse rows of setae, 4+4 anterior, 2+2 intermediate, and 3+3 posterior setae; caudal corner of paraterga dentiform, pointed, directed caually; 3+3 small tubercles in front of caudal margin (Fig. 9A & J). Tegument dull, prozona very finely shagreened, metaterga finely rugulose and microgranulate, surface below paraterga slightly more so. Postcollum metaterga with two transverse rows of setae, these being always borne on low, oblong, rounded tubercles: 2+2 in anterior (pre-sulcus) row, 3(4)+3(4) in posterior (postsulcus) one. Axial line visible both on pro- and metazona. Paraterga very strongly developed (Fig. 9A-G, J-L), especially so in ♂, subhorizontal to slightly upturned, lying level to or slightly above dorsum, thin in lateral view, like blunt blades, a little thicker only on pore-bearing segments, on postcollum segments always clearly projecting well behind tergal margin. Calluses delimited only dorsally, thin, especially so on poreless segments. Paraterga 2 broad, anterior edge angular, lateral edge with one larger and two smaller, but evident incisions in anterior 1/3; posterior edge evidently concave (Fig. 9A & J). Paraterga 3 and 4 subequal, like subsequent paraterga, anterior edge broadly rounded, bordered and fused to callus, lateral edge with a small incision in anterior third. Paraterga 16-19 with tip of caudal corner slightly curved mesad. Ozopores evident, lateral, lying in an ovoid groove at about 1/3 of metazonital length. Transverse sulcus present on metaterga 5-18, shallow, reaching bases of paraterga, smooth at bottom, slightly sinuate anteromedially (Fig. 9A, C, F, J-L). Stricture between pro- and metazona rather narrow, shallow, beaded at bottom down to base of paraterga. Pleurosternal carinae complete crests only on segments 2-7 (♂) (Fig. 9B & D) or 2-4 (♀), each with an evident sharp denticle caudally, thereafter increasingly reduced until segment 11 (♂, ♀). Epiproct (Fig. 9E, F & L) conical, flattened dorsoventrally, apical papillae small; tip subtruncate; preapical papillae small, but visible. Hypoproct (Fig. 9G) semi-circular, setiferous knobs at caudal edge well-separated.

Sterna sparsely setose, without modifications, but with a very evident, high, setose, central cone between ♂ coxae 4 (Fig. 9H & I). A conspicuous ridge in front of gonopod aperture. Legs long and slender, only slightly incrassate in ♂, midbody ones ca 1.4-1.5 (♂) or 1.1-1.2 times (♀) as long as body height, prefemora without modifications, tarsal brushes present until legs of segment 10.

Gonopods (Fig. 10) simple. Coxa long and slender, with several setae distodorsally. Prefemur densely setose, more than 2 times shorter than femorite (measured until beginning of solenomere). Femorite slender, evidently curved and slightly enlarged distad, “postfemoral” part demarcated by an oblique lateral sulcus; tip of solenophore evidently bifid, subterminal lobule with three minute denticles at distal margin.

Remarks.

This species is only known from southern Vietnam (Dalat and Peak Lang Biang).