Spinaxytes biloba Srisonchai, Enghoff & Panha
Srisonchai, Ruttapon, Enghoff, Henrik, Likhitrakarn, Natdanai & Panha, Somsak, 2018, A revision of dragon millipedes IV: the new genus Spinaxytes, with the description of nine new species (Diplopoda, Polydesmida, Paradoxosomatidae), ZooKeys 797, pp. 19-69: 19
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|Spinaxytes biloba Srisonchai, Enghoff & Panha|
Spinaxytes biloba Srisonchai, Enghoff & Panha sp. n. Figs 4 A–C, 5A, 6, 7, 8
Holotype. ♂, THAILAND, Surat Thani Province, Phanom District, near Khlong Phanom National Park, Pha Daeng, 8°53'41"N, 98°33'12"E, ca. 67 m a.s.l., 7 Aug. 2016, ASRU members leg. (CUMZ-pxDGT00205). Paratypes. 17 ♂♂, 24 ♀♀, same data as for holotype (CUMZ- pxDGT00206); 1 ♂, 1 ♀, same data as for holotype (ZMUC00040249); 1 ♂, 1 ♀, same data as for holotype (NHMW9423). Further specimens, not paratypes. 5 ♂♂, 3 ♀♀, THAILAND, Surat Thani Province, Phanom District, near Khlong Phanom National Park, Pha Daeng, 8°53'41"N, 98°33'12"E, ca. 67 m a.s.l., 6 Aug. 2015, ASRU members leg. (CUMZ).
The species name is an adjective, refers to the two additional process-like lobes on the solenophore (one on lamina lateralis and one on lamina medialis).
Differs from other species by having: metaterga 5-19 with 2+2 cones in anterior row and 3+3 cones in posterior row; sternal lobe between male coxae 4 subtrapeziform; male femora 8 and 9 with apophyses distally; lamina lateralis with an additional process-like protruding lobe; lamina medialis basally with an additional protruding process-like lobe.
SIZE. Length 15-17 mm (male), 16-18 mm (female); width of midbody metazona 1.0-1.2 mm (male), 1.3-1.5 mm (female). Width of rings 2 = 3 < 4 < collum < 5 < head = 6-17, thereafter body gradually tapering towards telson.
Colour (Figure 6A, B). Specimens in life brown/pale brown; paraterga brownish white; head, antennae (except whitish distal part of antennomeres 7 and 8) and collum brown; prozona, metaterga (except white spines in posterior row) and surface below paraterga brown/pale brown; sterna pale brown/whitish brown; epiproct and legs whitish brown; a few basal podomeres whitish brown/white.
Antennae. Reaching to body ring 7 or 8 (male) and 6 (female) when stretched dorsally.
Collum (Figure 7A). With three transverse rows of setiferous cones, 4+4 in anterior row, 1+1 in intermediate row and 2+2 in posterior row; with one inconspicuous setiferous notch at lateral margin; paraterga wing-like, quite short, tip blunt, elevated at ca. 15°-20° (male) 10°-20° (female), directed almost caudad.
Tegument. Quite shining; collum coarsely microgranulate; metaterga and surface below paraterga finely microgranulate.
Metaterga (Figure 7A, C, E). With two transverse rows of setiferous cones; metaterga 2-4 with 2+2 cones in anterior row and 2(3)+2(3) cones in posterior row; metaterga 5-19 with 2+2 cones in anterior row and 3+3 cones in posterior row; all cones subequal in length and size. An additional cone-like denticle at base of paraterga near anterior row of cones.
Paraterga (Figure 7 A–D, H). Quite short; directed dorsocaudad on body rings 3-17, elevated at ca. 60°-70° (male) 55°-70° (female), directed more caudad on body ring II and increasingly so on rings 18 and 19. Denticle of paraterga located at base of paraterga and very close to anterior row of cones on metaterga. Ozopore visible in lateral view.
Telson (Figure 7E, I, H). Epiproct quite long; tip subemarginate; lateral setiferous tubercles conspicuous; apical tubercles conspicuous. Hypoproct subtrapeziform, wide; caudal margin round (in some specimens subtruncate), with inconspicuous setiferous tubercles.
Sterna (Figs 4A; 7F, G). Sternal lobe between male coxae 4 subtrapeziform, broad, and thin, tips subtruncate, in situ directed ventroanteriad; posterior surface of sternal lobe with two pores borne on swollen and short lobe.
Legs (Figs 4B, C; 7J). Male femora 8 and 9 with apophyses distally.
Gonopods (Figs 5A, 8). Coxa shorter than femur. Prefemoral part ca. half as long as femur. Femur not enlarged distally. Postfemoral part broad. Mesal sulcus wide; lateral sulcus narrow. Solenophore subequal in size to postfemoral part: lamina lateralis small and short; with a protruding lobe, process-like, directed mesad; apically round: lamina medialis long; base enlarged and stout, slightly attenuated near the tip, basally with a protruding lobe, process-like, directed mesad; tip curving down, bifurcating into two small spines. Solenomere curving down, compressed in transverse section, tip directed posteriad.
Distribution and habitat
(Figure 6C). Known only from the type locality which is a small isolated limestone mountain between Khao Sok and Khlong Phanom National Parks. The new species blended perfectly with the humid rock walls, and most specimens were found inside rock holes/crevices. S. biloba sp. n. co-occurs with Desmoxytes cervina (Pocock, 1895) ( Srisonchai et al. 2018a) in the same habitat. Several attempts (2017-2018) have been made to find further specimens near the type locality, but none were found. As the new species has only been found at the type locality only, we regard S. biloba sp. n. as endemic to Thailand.
Among all Spinaxytes species, S. biloba sp. n. is obviously the smallest (length 15-18 mm, width of midbody metazona 1.0-1.5 mm), and the live pale brown colouration is lighter than that of other species.
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