Gigaxytes suratensis Srisonchai, Enghoff & Panha, 2018

Srisonchai, Ruttapon, Enghoff, Henrik, Likhitrakarn, Natdanai & Panha, Somsak, 2018, A revision of dragon millipedes III: the new genus Gigaxytes gen. nov., with the description of three new species (Diplopoda, Polydesmida, Paradoxosomatidae), European Journal of Taxonomy 463, pp. 1-43 : 31-39

Gigaxytes suratensis Srisonchai, Enghoff & Panha gen. et sp. nov.

urn:lsid:zoobank.org:act:8F348BCF-8785-40C0-AF0C-B5DA034FF7E1

( Figs 19–24 )

Diagnosis

Male femora 5, 6 and 7 with an apophysis. Similar in this respect to G. parvoterga gen. et sp. nov., but differs from this species by having paraterga longer; collum usually with 4+4 cones/spines (intermediate row); metaterga 2–8 usually with 4+4 cones/spines (anterior row), 4+4 cones/spines (intermediate row) and 4+4 cones/spines (posterior row); metaterga 9–12 usually with 5+5 cones/spines (anterior row), 5+5 cones/spines (intermediate row) and 5+5 cones/spines (posterior row); metaterga 13–19 usually with 6+6 cones/spines (anterior row), 6+6 cones/spines (intermediate row) and 6+6 cones/spines (posterior row).

Etymology

The specific epiteth is a Latin adjective, referring to the province where the type locality occurs.

Material examined

Holotype

THAILAND: ♂, Surat Thani Province, Phanom District, Ban Song Phi Nong , 8º50′54″ N, 98°44′16″ E, ca. 117 m a.s.l., 7 Aug. 2016, ASRU members leg. (CUMZ-pxDGT00182).

Paratypes

THAILAND: 3 ♂♂, 6 ♀♀, 13 juveniles, same data as for holotype (CUMZ-pxDGT00183-204); 1 ♂, 1 ♀, same data as for holotype ( ZMUC 00040248).

Additional specimens

THAILAND – Surat Thani Province: 1 ♂, 1 broken ♂ – right gonopod lost, 1 ♀, 1 broken ♀, 4 juveniles, Ban Ta Khun District, Ratchaprapa Dam, 8º57′22″ N, 98°48′22″ E, ca. 53 m a.s.l., 8 Oct. 2008, ASRU members leg. ( CUMZ); 1 ♂ – gonopods lost, Ban Ta Khun District, Khao Wong Water Supply Station, 8º55′47″ N, 98°56′25″ E, ca. 91 m a.s.l., 9 Oct. 2008, ASRU members leg. ( CUMZ); 1 ♂, Khirirat Nikhom District, Wat Satit Khirirom, 9º01′48″ N, 98°59′12″ E, ca. 50 m a.s.l., 10 Jul. 2017, ASRU members leg. ( CUMZ); 4 broken ♂♂, 3 broken ♂♂ – gonopods lost, 1 ♀, Phanom District, Khlong Phanom National Park, 8º52′44″ N, 98°40′26″ E, ca. 68 m a.s.l., 28 Aug. 2007, ASRU members leg. ( CUMZ); 1 juvenile, Phanom District, Wat Tham Wararam, 8º53′07″ N, 98°40′01″ E, ca. 51 m a.s.l., 5 Aug. 2014, ASRU members leg. ( CUMZ); 1 ♂ remaining rings 14–20, 1 ♂ – gonopods lost, 1 broken ♀, Unknown location (probably in Ban Ta Khun District), ASRU leg. ( CUMZ).

Description

SIZE. Length 36–40 mm (male), 38–40 mm (female); width of midbody metazona ca. 2.9 mm (male), 3.7 mm (female). Width of head <collum <2 ± 3 <4 <5–16, thereafter body gradually tapering towards telson.

COLOUR ( Fig. 19 A–E). Specimens in life with body pinkish brown; some specimens with a dark middorsal band; paraterga and antennae dark brown (except distal part of antennomere 7 and antennomere 8 whitish); head, epiproct and legs brown; metaterga, prozona and surface below paraterga (upper part) pinkish brown; collum pinkish brown/brown; surface below paraterga (lower part) brownish pink; tip of paraterga and sterna pale brown to whitish; a few basal podomeres pale brown. Colour in alcohol: after 10 years changed to pale brown; head, antennae, collum, metaterga, paraterga, surface below paraterga, sterna, epiproct and legs pale brown.

COLLUM ( Fig. 20A ). With three transverse rows of setiferous cones/spines, 5(6)+5 cones/spines in anterior row, 4(3)+4(3) cones/spines in intermediate row and 4(3/5)+4(5) cones/spines in posterior row (lateral cones/spines of anterior row located at base of collum paraterga; lateral cones/spines of posterior row displaced anteriad almost halfway to intermediate); paraterga of collum elevated at ca. 30º–45º.

ANTENNAE ( Fig. 20D ). Moderately long and slender, reaching to body ring 5 or 6 (male) and 4 or 5 (female) when stretched dorsally.

TEGUMENT. Stricture between prozona and metazona wide, quite deep.

METATERGA ( Fig. 20 A–C). With three transverse rows of setiferous cones/spines; metaterga 2–8 with 4(5)+4(5) cones/spines in anterior row, 4(3)+4(3/5) cones/spines in intermediate row and 4(3/5)+4(3/5) cones/spines in posterior row; metaterga 9–12 with 5(6/7)+5(6) cones/spines in anterior row, 5(6)+5(6) cones/spines in intermediate row and 5(6/7)+5(6/7) cones/spines in posterior row; metaterga 13–19 with 6(5/7/8)+6(5/7/8) cones/spines in anterior row, 6(5/7/8)+6(5/7/8) cones/spines in intermediate row and 6(5/7/8)+6(5/7/8) cones/spines in posterior row.

PLEUROSTERNAL CARINAE. On body ring 2 long, crest-like; on ring 3 a long ridge; on ring 4 a short ridge; thereafter missing.

PARATERGA ( Figs 20 A–C, I, 21A–B). Moderately long, directed caudolaterad on body rings 2–17, elevated at ca. 45º–60º (male) 40º–50º (female), directed increasingly caudad on body rings 18–19.

TELSON ( Fig. 21 C–G). Tip of epiproct usually subtruncate (in some specimen slightly emarginate); apical tubercles inconspicuous. Hypoproct subtrapeziform; caudal margin usually subtruncate (in some specimens slightly round), with inconspicuous setiferous tubercles.

STERNUM ( Fig. 21 H–J). On body ring 5 with a swollen lobe; posterior surface of lobe with a pore borne on a short cylindrical stalk.

LEGS ( Fig. 20 E–H). Male femora 5, 6 and 7 with an apophysis.

GONOPODS ( Figs 22–23 ). Coxa subequal in length to femorite. Cannula quite short and stout. Femorite long, slender, curved. Solenophore wide laterally: lamina lateralis broad: lamina medialis very wide, distally blunt, in situ directed mesoventrad.

Distribution and habitat

Gigaxytes suratensis gen. et sp. nov. is known only from Surat Thani Province. It has been collected from limestone habitats hiding under dead leaves. We cound not access many isolated limestone moutains nearby the type locality, we assume, however, that this species might have a distribution running along the huge limestone mountain ranges in Khaosok and Khlong Phanom National Parks. According to the current data, the new species is dispersed narrowly, we therefore regard G. suratensis gen. et sp. nov. as endemic for Thailand. The new species was found together with Desmoxytes corythosaurus Srisonchai, Enghoff & Panha, 2018 at Ban Song Phi Nong and Wat Satit Khirirom; Desmoxytes cervina at Wat Satit Khirirom.

Remarks

Across the range of this species there are some variations in tip of epiproct (subtruncate in some specimens, slightly emarginate in others) and in shape of caudal margin of hypoproct (subtruncate in some specimens, in others slightly round).

Figures

Fig. 19. A–E. Photographs of live Gigaxytes suratensis Srisonchai, Enghoff & Panha gen. et sp. nov. A. Ƌ paratype, specimen from Ban Song Phi Nong. B. Ƌ, specimen from Wat Satit Khirirom. C. ♀ paratype, specimen from Ban Song Phi Nong. D. Mating couple (paratypes). E. Juvenile. F. Habitat.

Fig. 20. Gigaxytes suratensis Srisonchai, Enghoff & Panha gen. et sp. nov., ³ paratype. A. Anterior body part. B. Body rings 8–10. C. Posteriormost body rings and telson. D. Head and antenna. E. Ƌ leg 5 (right). F. Ƌ leg 6 (right). G. Ƌ leg 7 (right). H. Ƌ leg 13 (right). I. Midbody ring.

Fig. 21. Gigaxytes suratensis Srisonchai, Enghoff & Panha gen. et sp. nov., ³ paratype. A. Body rings 8–10. B. Paraterga of ring 10 (arrowhead points to ozopore). C–D. Last ring and telson. E. Hypoproct. F–G. Epiproct. H–J. Sternal lobe between coxae 4.

Fig. 22. Gigaxytes suratensis Srisonchai, Enghoff & Panha gen. et sp. nov., ³ paratype – right gonopod. A. Mesal view. B. Lateral view. C. Ventral view. D. Dorsal view.

Fig. 23. Gigaxytes suratensis Srisonchai, Enghoff & Panha gen. et sp. nov., ³, paratype – right gonopod. A. Lateral view. B. Mesal view. C. Ventral view. D, F. Subdorsal view. E. Dorsal view.

Fig. 24. Known distribution of all Gigaxytes gen. nov. species (black symbol = type locality, white symbol = other localities).