Streptogonopus montanus, Nguyen, Anh D., Jang, Kuem-Hee & Hwang, Ui-Wook, 2016

Nguyen, Anh D., Jang, Kuem-Hee & Hwang, Ui-Wook, 2016, The first record of the millipede genus Streptogonopus Attems, 1914 from Vietnam, with description of a new species (Diplopoda, Polydesmida, Paradoxosomatidae), ZooKeys 601, pp. 111-118 : 112-115

Taxon classification Animalia Polydesmida Paradoxosomatidae

Streptogonopus montanus sp. n. Figs 1, 2, 3

Material examined.

Holotype: 1 male (IEBR-Myr 131H) Vietnam, Kon Tum Prov., Ngoc Linh Mts. (107°58'30"E; 15°04'09"N), primary forest, 1,900 m a.s.l., pitfall traps, 29 March - 4 April 2006, leg. Nguyen A.D.

Paratypes: 1 female (IEBR-Myr 131P) same data as holotype; 1 male (IEBR-Myr 145) same locality, but 1,900-2,100 m a.s.l., 21 March– 9 April 2006; 2 males, 1 juvenile (IEBR-Myr 132) same locality, but 1,800 m a.s.l., pitfall traps, 20-26 March 2006, all leg. Nguyen A.D.

Diagnosis.

This species is recognised by the gonopod femorite grooved mesally, slightly curved and expanded distally, without processes; solenophore and solenomere coiled twice, equal in length. Solenophore with a small spine at ½ its length.

Etymology.

“montanus”, an adjective to emphasise that the species has been found in a mountainous region.

Description.

Length 26.7-28.2 mm (male) and 30 mm (female). Width of midbody pro- and metazonae 2.3-2.5 mm (male), 2.8 mm (female) and 2.7-2.9 mm (male), 3.1 mm (female), respectively.

Coloration (Fig. 1 A–B, D): body generally castaneous or reddish brown, except legs, antenna and sterna somewhat brownish yellow.

Head subequal to collum in width; clypeolabrum modestly setose. Epicranial suture distinct. Antennae slender and long, reaching the end of segment 4 when stretched posteriorly. Antennomere 2=3=4=5=6>1>7 in length.

Collum (Fig. 1B) somewhat narrower than segment 2 in width. Surface dull and weakly wrinkled, with three rows of 4+4, 4+4 and 2+2 setae. Transverse sulcus absent. Axial line thin and evident. Paraterga modestly developed, subtriangular with broadly rounded anterior corner.

In width, segment 3<4<2=5-16, thereafter gradually tapering towards telson (Figs 1B, 1D). Prozonae shagreened. Metaterga dull, somewhat rugose with short longitudinal wrinkles, and with a row of 3+3 setae near anterior margin and a row of 3(4)+3(4) small knobs near posterior margin. Transverse sulcus starting present on metatergum 5, rather broad, not reaching base of paraterga, neither striolate nor beaded at bottom. Constriction between pro- and metazonae wide, striolate at bottom. Pleura with dense microgranulation. Pleurosternal carinae well developed on segments 2-7, reduced as a small caudal denticle on segments 8-14, then missing on subsequent segments.

Paraterga (pa) (Fig. 1 A–B, D) modestly developed, wing-shaped, set lower than metatergal surface. Caudolateral corner pointed, spiniform on caudal segments. Paraterga surpassing posterior contour of metaterga, but not reaching next metaterga. Calluses very small, somewhat wanting on poreless paraterga, with a long seta laterally. Ozopores (oz) located near caudolateral corner of paraterga 5, 7, 9-10, 12-13, 15-19.

Epiproct (ep) (Fig. 1D, E–F) long, but broadly truncated, with four spinnerets at tip. Hypoproct (hp) roundly triangular, with two separated, distolateral, setiferous knobs.

Sterna (Figs 1C, 1E) moderately setose, without modifications except sternum 5 with two independent setiferous projections between coxae of legpair 4 (Fig. 1G).

Legs (Figs 1 A–E) thin and slender, about 1.3 times as long as midbody height. Prefemora not swollen. Femora without modification. Tarsal brushes present only on pre-gonopodal legs.

Gonopods relatively simple (Figs 2-3). Coxite long, subcylindrical; distoventral part sparsely setose. Prefemorite (pref) densely setose, separated laterally from femorite by transverse sulcus. Femorite (fe) grooved mesally, slightly curved and expanded distad, with distolateral processes (dp); demarcated laterally from the postfemoral region (= solenophore) by an oblique sulcus. Solenophore (sph) and solenomere (sl) coiled more or less twice, equal in length. Solenophore with a small spine (sp) at half its length. Seminal groove (sg) running mesodorsad entirely mesally on femorite before entering the flagelliform solenomere.

Remarks.

This new species could be assigned to the second group characterised by modestly developed paraterga. However, it differs from three its congeners, Streptogonopus neglectus , Streptogonopus phipsoni , and Streptogonopus nitens in solenomere and solenophore being equal in length and strongly coiled twice and the solenophore having a small spine at its middle.