Tonkinosoma jeekeli, Nguyen, Anh D., 2011

Nguyen, Anh D., 2011, A review of the millipede tribe Tonkinosomatini (Diplopoda: Polydesmida: Paradoxosomatidae) from Vietnam, Zootaxa 3036, pp. 58-68 : 64-67

Genus Tonkinosoma Jeekel, 1953

Tonkinosoma jeekeli sp. nov. ( Figs. 6–8 . Map 1)

Material examined. HOLOTYPE: 13 (IEBR-128H), Vietnam, Ninh Binh Province, Cuc Phuong National Park, forest, 15 September 2006, leg. Luu Van Hien.

PARATYPES: 23, 3ƤƤ (IEBR-128P), same data as holotype; 3 3, (IEBR-129), Vietnam, Hai Phong Province, Cat Ba National Park, primary forest, 10 August 2006, leg. Nguyen Tri Tien.

Etymology. This species is dedicated to the late Dr. C.A.W. Jeekel, a prominent specialist in Diplopoda, who established the genus Tonkinosoma .

Diagnosis. This species differs from its congener Tonkinosoma flexipes Jeekel, 1953 , in following characters: sternite V with two independent small lamina between coxae 4, and without any modification between coxae 5; gonopod femorite much broader and constricted distally; solenophore with both well-developed lamina medialis and lamina lateralis.

Description. Size: body 42.6–47.5mm (male), 57mm (female) in length, width of midbody pro- and metazona 4.2–4.3mm (male), 4.8 (female) and 5.3–5.8mm (male), 7.2mm (female), respectively. Holotype 47.5mm long and width of midbody pro- and metazoan 4.3mm and 5.8mm, respectively.

Coloration: body in general reddish brown; legs, antenna and sterna yellowish brown; paraterga, marginally rear part of metaterga and pleura paler ( Figs. 6 A–C).

Head: a bit smaller than collum, modestly setose on labrum, but sparsely on area between antennal sockets. Frons slightly convex. Epicranical suture obviously distinct. Antenna short, claviform, ca. reaching to body ring 3 laterally. Antennomere 1 <7<6<2=5 ( Fig. 6 A).

Collum: slightly broader than body ring 2, subtrapeziform, surface shining, smooth, without any rugosity or wrinkles, and with traces of 2 rows of 4+4 and 3+3 setae in front margin and in middle, respectively. Paratergum subtriangular, poorly-developed. Axial line wanting.

Body rings: Width of body ring 4<3<2=5, parallel-sided on body rings 5–16, thereafter tapering gradually posterior. Surface smooth, shining, with traces of a row of 3+3 setae before transverse sulcus, which starts on metatergum 5, however, very superficial and vague ( Fig. 7 A). Paraterga modestly developed, set lower than metatergal surface ( Fig. 6 A&C). Caudal corner acute, surpassing rear contour ( Figs. 6 A&C, 7A). Pleurosternal carinae like small, oblique keels, present until body ring 10, and missing on subsequent ones ( Fig. 6 A&C). Axial line thin, visible. Stricture dividing pro- and metazona thin, narrow and striate.

Sterna: modestly setose, cross-impression moderate in terms of both longitudinal and transverse suture, without any modification except two independent lamina between coxae 4 ( Fig. 7 B).

Legs: rather short, but slender, about 1.1 times (male) as long as body height. No adenostyle or any other modification. Tarsi without setose brushes.

Telson: Epiproct short, broadly truncated with four spinnerets at tip ( Fig. 7 D). Paraproct sub-semicircular with two setiferous knobs on disk. Hypoproct subtriangular with two distolateral setiferous knobs ( Fig. 7 C).

Gonopods: ( Figs. 7 E–F, 8A–C) relatively simple. Coxite subcylindrical, slender and as long as femorite. Prefemur subrectangular, densely setose as usual, set off from femorite by a transversal suture (su) laterally. Femorite (fe) stout, expending in middle with a smaller distal part, without any femoral processes. Postfemoral region (= solenophore, sph) separated from femorite by an oblique sulcus laterally, curved down ventrally, and strongly twisted ventromesad. Both lamina medialis (lm) and lamina lateralis (ll) present. The former with a triangular lobe (tl) at distal part. Tip of solenophore acute.

Seminal groove running entirely on mesal side before entering flagiliform solenomere, which is almost sheathed by solenophore.

Remarks. Jeekel (1953) proposed a monotypic genus Tonkinosoma for a new species Tonkinosoma flexipes Jeekel, 1953 , from Mauson Mt. (Lang Son province). The generic diagnosis was given to its species as well.

Hoffman (1961), when he created a new genus Szechuanella for a new species S. tenebra from China, discussed and compared both genera, Tonkinosoma and Szechuanella . He suggested that S. tenebra and T. flexipes are very similar in gonopod structure except for the degree of curvature of the solenophore, a presence of pleurosternal carinae in Tonkinosoma , and also in small detail of the solenophore structure. Later Hoffman (1963) placed a species Nedyopus variatus Attems, 1953 into his genus Szechuanella , and maintained his separation of the two genera Tonkinosoma and Szechuanella . However, based on fresh material, the two genera are obviously distinguished by a presence/absence of additional processes in the postfemoral region of the gonopod, femorite enlarged or not, and the presence of pleurosternal carinae as well.

In brief, the genus Tonkinosoma Jeekel, 1953 currently comprises two species and is distribute in the north of Vietnam (Map 1).

MAP 1. Distribution of all Tonkinosomatini species. 1: Wushan, Szechuan Province, China; 2: Sapa, Lao Cai province, Vietnam; 3: Mau Son Mt., Lang Son Province, Vietnam; 4: Xuan Son National Park (NP), Phu Tho Province, Vietnam; 5: Cat Ba Island, Hai Phong Province, Vietnam; 6: Cuc Phuong NP, Ninh Binh Province, Vietnam; 7: Pu Mat NP, Nghe An Province, Vietnam; 8: Huong Son, Ha Tinh Province, Vietnam; 9: Phong Nha – Ke Bang NP, Quang Binh Province; 10: Loxo pass, Kon Tum Province, Vietnam.

Figures

FIGURE 6. Tonkinosoma jeekeli sp. nov., holotype body: anterior part, lateral view (A), posterior part, lateral view (C), whole body, dorsal view (B). Scale bar = 10 mm.

FIGURE 7. Tonkinosoma jeekeli sp. nov., holotype, body ring 10 – 11, dorsal view (A); sternite V, ventral view (B); hypop-roct, ventral view (C); epiproct, ventral view (D); left gonopod, lateral view (E), mesal view (F). Scale bar = 1 mm.

FIGURE 8. Tonkinosoma jeekeli sp. nov., paratype, left gonopod, mesal view (A), lateral view (B); Tip of gonopod, lateral view (C).