Orthomorpha arboricola (Attems, 1937)

Likhitrakarn, Natdanai, Golovatch, Sergei I., Semenyuk, Irina, Efeykin, Boris D. & Panha, Somsak, 2019, Review of the millipede genus Orthomorpha Bollman, 1893 (Diplopoda, Polydesmida, Paradoxosomatidae) in Vietnam, with several new records and descriptions of two new species, ZooKeys 898, pp. 121-158 : 121

Orthomorpha arboricola (Attems, 1937) Figs 1 , 2

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); Likhitrakarn et al. 2011: 18 (D).

Old records.

Vietnam, Lamdong Province, Dalat, 1,500 m a.s.l.; Lamdong Province, Langbian Mountain, Trąm Hành (= Arbre-Broyé) ( Attems 1937, 1938).

New material examined.

2 ♂ (ZMUM), Vietnam, Khanh Hoa Province, Hon Ba Nature Reserve, 12°07'02"N, 108°56'45"E, 1,550 m a.s.l., mixed mossy forest on mountain ridge, on forest floor, night time, 27.VI.2018, I. Semenyuk leg.

Descriptive notes.

Length 40-41 mm (♂), width of midbody pro- and metazonae 2.7-2.8 and 4.3-4.4 mm (♂), respectively.

Live colouration ( Fig. 1A ) and colouration in alcohol, after one year of preservation, similar, only slightly faded in fixed material, yellow-brown to brown ( Fig. 1 B–F ), paraterga, most of mid-dorsal parts of metaterga and tip of epiproct orange-yellow to light yellow, legs and sterna light dark brown to light yellowish, antennae blackish ( Fig. 1A, B ).

All characters as in the available descriptions ( Attems 1937; Likhitrakarn et al. 2011), except as follows. Posterior (postsulcus) transverse row of 3(4)+3(4) low, setigerous, oblong, rounded tubercles on postcollum metaterga. A prominent, tongue-shaped, rounded, setose cone or lobe between ♂ coxae 4 ( Fig. 1I, J ). Pleurosternal carinae complete crests only on segments 2-4 (♂) ( Fig. 1B, D ), each with an evident sharp denticle caudally, thereafter increasingly reduced until segment 11. Solenophore tip very faintly bidentate, with terminal tooth bearing a minute denticle at base ( Fig. 2 ); solenomere long and flagelliform, as usual in the genus.

Remarks.

This species is known not only from type material from southern Vietnam (Dalat and Peak Lang Biang, at both sites found to coexist with O. rotundicollis (Attems, 1937)), but also from the new samples cited above. The types have recently been redescribed by Likhitrakarn et al. (2011), while the above new material shows only minor variations.

Figures

Figure 1. Orthomorpha arboricola (Attems, 1937), ♂ from Hon Ba National Park A habitus and live colouration B, C anterior part of body, dorsal and lateral views, respectively D, E segments 10 and 11, dorsal and lateral views, respectively F-H posterior part of body, dorsal, ventral and lateral views, respectively I, J sternal cone between coxae 4, subcaudal and sublateral views, respectively.

Figure 2. Orthomorpha arboricola (Attems, 1937), left gonopod A, B mesal and lateral views, respectively C tip of right gonopod, lateral view. Scale bars: 0.5 mm.