Orthomorpha insularis Pocock, 1895

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 : 79-83

Orthomorpha insularis Pocock, 1895 Figs 9196

Orthomorpha insularis Pocock 1895: 817 (D).

Orthomorpha clivicola Pocock 1895: 819 (D).

Orthomorpha palonensis Pocock 1895: 820 (D).

Orthomorpha monticola Pocock 1895: 820 (D).

Orthomorpha gestri Pocock 1895: 820 (D).

Orthomorpha gestri - Attems 1936: 205 (M, R); 1937: 94 (M); Jeekel 1963: 265 (M); 1964: 361 (M); 1968: 56 (M).

Orthomorpha Gestri - Attems 1898: 328 (D); 1914: 238 (M).

Orthomorpha monticola - Attems 1898: 328 (D); 1914: 238 (M); 1936: 205 (M, R); 1937: 94 (M); Jeekel 1963: 265 (M); 1964: 361 (M, D); 1968: 56 (M).

Orthomorpha palonensis - Attems 1898: 328 (D); 1914: 238 (M); 1936: 205 (M, R); 1937: 94 (M); Jeekel 1963: 265 (M); 1964: 361 (M); 1968: 56 (M).

Orthomorpha clivicola - Attems 1898: 328 (D); 1914: 238 (M); 1936: 204 (M, R); 1937: 93 (M); Jeekel 1963: 265 (M); 1964: 361 (M); 1968: 56 (M).

Orthomorpha insularis - Attems 1898: 328 (D); 1914: 238 (M); Jeekel 1963: 265 (M); 1964: 361 (M, D); 1968: 56 (M); 1970: 293 (D); Hoffman 1977: 700 (M); Golovatch 1998: 42 (D).

Orthomorpha karschi insularis Attems 1936: 199 (D).

Orthomorpha karschii insularis - Attems 1937: 71 (D).

Orthomorpha karschii intercedens Attems 1937: 71 (D).

Orthomorpha intercedens - Jeekel 1963: 265 (M); 1964: 361 (M); 1968: 56 (M); 1970: 293 (D); Enghoff 2005: 97 (M, R); Decker 2010: 31 (R).

Material examined.

2 ♀ (CUMZ), Thailand, Mae Hong Son Prov., Mueang Mae Hong Son Distr., Tham Woa Temple, 19°53'33"N, 98°08'40"E, 19.07.2008, leg. R. Chanabun. 2 ♂, 1 ♀ (CUMZ), Chiang Mai Prov., Mueang Chiang Mai Distr., Doi Suthep National Park, ca 1290 m, 18°48'09"N, 98°54'12"E, 23.04.2009, leg. N. Likhitrakarn. 2 ♂ (CUMZ), same locality, 28.11.2009, leg. N. Likhitrakarn. 1 ♀ (ZMUC), 1 ♀ (ZMUM), 2 ♂, 1 ♀, 2 juv. (CUMZ), same Prov., Chiang Dao Distr., Palong Temple, ca 470 m, 19°24'13"N, 98°55'16"E, 28.09.2010, leg. N. Likhitrakarn. 1 ♂ (CUMZ), Phayao Prov., Phu Sang Distr., Phu Sang National Park, 20°06'02"N, 100°37'56"E, 24.10.2008, leg. C. Sutcharit. 1 ♂, 1 ♀ (CUMZ), Tak Prov., Mae Sot Distr., Doi Mu Soe, 17°18'70"N, 99°33'50"E, 5.10.2008, leg. C. Sutcharit. 1 ♂, same Prov., Tha Song Yang Distr., at Mae Usu Cave, ca 140 m, 17°18'16"N, 98°09'21"E, 30.05.2009, leg. N. Likhitrakarn. 1 ♂ (CUMZ), same Prov., Umphang Distr., near Umphang City, ca 490 m 16°02'20"N, 98°52'0"E, 06.07.2009, leg. N. Likhitrakarn. 2 ♂, 1 ♀ (CUMZ), Kanchanaburi Prov., Thong Pha Phum Distr., Krienkravia Waterfall, ca 260 m, 14°58'55"N, 98°37'53"E, 10.07.2009, leg. C. Sutcharit. 2 ♀ (CUMZ), same locality, 08.05.2010, leg. N. Likhitrakarn. 1 ♀ (CUMZ), same locality, 19.12.2010, leg. N. Likhitrakarn. 1 ♂ (ZMUC), 1 ♂ (ZMUM), 3 ♂, 2 ♀ (CUMZ), same Distr., Thong Pha Phum, 15.08.2007, leg. S. Panha. 1 ♀, 11 juv. (CUMZ), same Prov., Sai Yok Distr., Daowadueng Cave National Park, ca 210 m, 14°28'12"N, 98°49'58"E, 11.07.2009, leg. C. Sutcharit.

Descriptive notes.

Length 33-41.5 mm (♂) to 34-51 mm (♀), width of midbody pro- and metazona 3.1-4.0 and 4.9-5.7 mm (♂), 3.2-4.5 and 5.2-7.0 mm (♀), respectively.

Coloration of live animals (Figs 91A & 92A) blackish brown with rather poorly contrasting light orange-brown to light brown paraterga and epiproct, rear halves to nearly entire metaterga sometimes a little more infuscate, brownish; coloration upon long-term preservation in alcohol basically same, but paraterga, epiproct, most of metatergal surface, as well as frontodorsal parts of prozona contrasting pallid, yellowish or light grey-brown (Figs 91B-H, K-M & 92B-H). A light centrocaudal spot to a broad caudal band on the collum seems to be characteristic of this species, despite its size variation from small and vague to large and clear in alcohol-preserved material (Figs 91B & C, 92B & C).

Antennae rather long, clavate (antennomere 6 broadest), extending behind body segment 3 (♂) or 2 (♀) dorsally.

Collum with caudal corner of paraterga ranging from obtusangular (Fig. 92A & B), via subrectangular (Fig. 91B & C), to evidently acutangular. Calluses of paraterga always very broad and their caudal corners mostly extending only to hind tergal margin, but sometimes, even within a single population, calluses slightly narrower, not reaching rear tergal margin, forming instead a subrectangular turn mesally (Figs 91B-E & 92B-E), extending increasingly beyond rear margin in hind body portion to only several caudal segments, with caudal tip remaining from acute and pointed thoughout (♂ from Phu Sang National Park, Fig. 91K) to mostly narrowly rounded (♂ from Paplong Temple, Fig. 91L & M). Metatergal sulcus visible on segments 5-18 (♂, ♀). Pleurosternal carinae expressed as complete high crests with a sharp caudal tooth on segments 2-4, thereafter increasingly well divided into a front bulge and a caudal tooth on segments 5-7, both increasingly strongly reduced in size until segment 15 or 16 (♂, ♀).

Midbody legs ca 1.1-1.4 (♂) to 0.9-1.3 times (♀) as long as body height.

Tip of gonopod trifid, with terminal lobule longest, middle spiniform prong sometimes being shorter than usual (Figs 93-96).

Remarks.

Jeekel (1970), when redescribing Orthomorpha insularis Pocock, 1895, from material from Myanmar, also emphasized clear variation in the width of the calluses and of the outlines of some paraterga. This has allowed him to synonymize several other nominate congeners, revised from type material from Myanmar, with Orthomorpha insularis (see catalogue section above). The above abundant material from Thailand confirms a profound variation range in size, coloration, shapes of the collum and following paraterga etc. This variation is deemed to be only individual, as our examination of larger series shows. No complete redescription is provided here, because that of Jeekel (1970) is detailed enough.

This species appears to be widespread over much of Thailand, as well as in the adjacent parts of Myanmar (Map 4). Enghoff (2005), Decker (2010) and Likhitrakarn et al. (2010a), in their faunistic accounts on Thai millipedes, mistakenly referred to Orthomorpha intercedens , which is long known to be only a junior synonym of Orthomorpha insularis (see Jeekel 1970).