Tylopus acuminatus, Likhitrakarn & Golovatch & Panha, 2016

Likhitrakarn, Natdanai, Golovatch, Sergei I. & Panha, Somsak, 2016, The millipede genus Tylopus Jeekel, 1968 (Diplopoda, Polydesmida, Paradoxosomatidae), with a key and descriptions of eight new species from Indochina, European Journal of Taxonomy 195, pp. 1-47 : 17-22

Tylopus acuminatus sp. nov.

urn:lsid:zoobank.org:act:C0DB482F-EE58-4385-9733-7D2E724DEFED

Figs 12–15 , 26

Diagnosis

Very similar to T. jeekeli Golovatch & Enghoff, 1993 and T. parajeekeli Likhitrakarn, Golovatch, Prateepasen & Panha, 2010 , especially in its gonopod conformation, but differs in process h being higher and more strongly flattened, pointed, while the sternal lobe between Ƌ coxae 4 linguiform and larger.

Etymology

To emphasize the acuminate processes h on the gonopod; adjective.

Material examined

Holotype

LAOS: Ƌ, Ban Sin Chai, Boun Neua , Phongsali, 21°31'50" N, 101°51'45" E, ca 820 m a.s.l., 15 Oct. 2014, leg. C. Sutcharit & R. Srisonchai ( CUMZ).

Paratypes

LAOS: 1 Ƌ, 1 ♀, Phuthalang forest protected area, Boun Neua, Phongsali, 21°37'30" N, 101°55'55" E, ca 1125 m a.s.l., 16 Oct. 2014 ( CUMZ); 1 Ƌ, 2 ♀♀, Phufa, Boun Neua, Phongsali, 21°41'05" N, 102°06'35" E, ca 1470 m a.s.l, 16 Oct. 2014 ( CUMZ); 1 ♀, near Ban Borkhun, Boun Neua, Phongsali, 21°27'57" N, 101°47'20" E, ca 880 m a.s.l., 18 Oct. 2014 ( CUMZ); 1 ♀, Khoua, Phongsali, 21°11'55" N, 102°06'40" E, ca 840 m a.s.l., 15 Oct. 2014 ( CUMZ); 1 Ƌ, 1 ♀ ( NHMW), 1 Ƌ ( ZMUM ρ3059), Ban Na Thong, Namo, Oudomxay, 20°52'25" N, 101°47'00" E, ca 650 m a.s.l., 14 Oct. 2014; 1 Ƌ, Phagneung Phoukulom Waterfall, Sing, Luang Namtha, 21°07'15" N, 101°14'40" E, ca 900 m a.s.l., 13 Oct. 2014, all leg. C. Sutcharit & R. Srisonchai ( ZMUC).

Description

MEASUREMENTS AND COLOUR. Length 24.5–31.6 (Ƌ) or 24.3–31.5 mm (♀), width of midbody pro- and metazonae 1.98–2.6 and 2.95–3.6 mm (Ƌ) or 2.7–2.9 and 3.1–4.2 mm (♀), respectively. Live coloration dark brown ( Fig. 12A ); antennae and epiproct light brown; legs yellow-brown. Coloration of alcohol

material after one year of preservation faded to brown to yellow-brown; head, antennae, epiproct light brown to yellow-brown, legs and venter yellow-brown to light yellow ( Fig. 12 B–J).

HEAD. Clypeolabral region densely, vertex sparsely, setose; epicranial suture distinct. Antennae ( Fig. 12A ) short, surpassing body segment 2 (Ƌ, ♀) when stretched dorsally. In width, head <segment 3 <collum <segment 4 <2 <5–16 (Ƌ), or head <segment 3 <4 <collum <segment 2 <5–16 (♀); thereafter body gently and gradually tapering. Collum with three transverse rows of setae: 4+4 anterior, 1+1 intermediate and 2+2 posterior paraterga declined ventrad, with a small lateral incision at about midway; caudal corner very broadly rounded, not surpassing rear tergal margin ( Fig. 12C ).

BODY. Tegument smooth and shining, prozonae finely shagreened, metaterga smooth and leathery ( Fig. 12B, D, F ); surface below paraterga microgranulate ( Fig. 12C, E, H ). Postcollum metaterga with an anterior transverse row of 2+2, mostly abraded setae; posterior row barely traceable as 4+4 insertion points, these being better visible on segments 17–19 ( Fig. 12F ). Tergal setae simple and slender, about 2/3 as long as metaterga. Axial line traceable on prozonae and anterior halves of metazonae. Paraterga well-developed ( Fig. 12 B–F, H), especially so in Ƌ, set rather high (at upper 1/3 of body height), slightly upturned, but lying below dorsum; anterior edge broadly rounded and narrowly bordered, fused to callus; caudal corner very narrowly rounded, drawn behind tergal margin, increasingly protruding and pointed starting with segment 16 ( Fig. 12F, H ). Paraterga 2 with two evident incisions at lateral edge in anterior 1/3. Paraterga 3 and 4 each with two similar incisions at lateral edge, one in anterior 1/3, the other about the middle. Following paraterga each with one evident lateral incision in anterior 1/3 and, in pore-bearing segments, a very small denticle in the middle ( Fig. 12B, D, F ). Calluses on paraterga delimited by a sulcus both dorsally and ventrally. Ozopores evident, lateral, lying in an ovoid groove at about 1/3 of metatergal length in front of posterior edge of metaterga. Transverse sulcus evident on metaterga 5–17, incomplete on metaterga 18, narrow, line-shaped, rather deep, ribbed at bottom, not reaching bases of paraterga ( Fig. 12B, D, F ). Stricture between pro- and metazonae evident, wide and deep, ribbed at bottom down to base of paraterga ( Fig. 12B, D – F ). Pleurosternal carinae complete crests with a sharp caudal tooth on segments 2 and 3 (Ƌ, ♀), increasingly reduced and remaining a strong, sharp, caudal tooth on segments 4–8, retained as a small sharp tooth on segments 9–16, a minute tooth on segment 17 (Ƌ), or an evident, sharp, caudal tooth on segments 4–15, then remaining a small rounded tooth on segment 16, thereafter missing (♀) ( Fig. 12C, E, H ). Epiproct ( Fig. 12 F–H) conical, flattened dorsoventrally, with two evident, rounded, apical papillae; tip subtruncate; lateral pre-apical papillae evident, lying close to tip. Hypoproct ( Fig. 12G ) roundly subtrapeziform, setigerous knobs at caudal edge small and well-separated.

STERNA. Moderately setose and densely microtuberculate; cross-impressing shallow; an entire, linguiform, sternal lobe between Ƌ coxae 4 ( Fig. 12I – J ). A paramedian pair of conspicuous ridges in front of gonopod aperture. Legs rather long and slender, midbody ones ca 1.2–1.3 (Ƌ) or 1.0–1.1 (♀) as long as body height; Ƌ legs with prefemora distinctly swollen laterally, acropodites with particularly dense setae ventrally ( Fig. 13C ), but tarsal brushes absent.

GONOPOD. Rather simple ( Figs 13A – B , 14 – 15 ); coxa slightly curved caudad, sparsely setose distoventrally. Femorite slightly curved and stout, with an evident mesal groove and a clear distolateral sulcus demarcating a postfemoral part; process h prominent, evidently curved, pointed, with a small, but evident dorsal tooth and sometimes with a small ventral denticle ( Fig. 13A – B ); spine z pointed, sometimes small ( Fig. 15G ); solenophore (sph) large, expanded, flattened and typically coiled.

Remark

This species shows slight variations in gonopod structure, process h often being rather narrow to slightly broader, while spine z small to slightly broader ( Fig. 15 ).

Figures

Fig. 12. Tylopus acuminatus sp. nov., holotype, Ƌ. A. Habitus, live coloration. 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 cones between coxae 4, caudal and sublateral views, respectively.

Fig. 13. Tylopus acuminatus sp. nov., holotype, Ƌ, right gonopod. A–B. Lateral and mesal views, respectively. C. Leg 13. Scale bar: A–B. 0.5 mm; C = no scale bar. Abbreviations are explained in the text.

Fig. 14. Tylopus acuminatus sp. nov., holotype, Ƌ, right gonopod. A–B. Mesal and lateral views, respectively. C–F. Distal part, sublateral, submesal, subcaudal and suboral views, respectively. Scale bars = 0.2 mm.

Fig. 15. Tylopus acuminatus sp. nov., paratype, Ƌ, from Phufa (A–B), paratype, Ƌ, from Phuthalang forest protected area (C–D), paratype, Ƌ, from forest near road (E), paratype, Ƌ, from Ban Na Thong (F), paratype, Ƌ, from Phagneung Phoukulom waterfall (G–H). A–H. Distal part, sublateral, submesal, dorsal, subdorsal, dorsal, subdorsal, ventral and dorsal views, respectively. Scale bars = 0.2 mm. Red colour shows process h. Green colour shows spine z.

Fig. 26. Distribution of the new eight species of Tylopus. Filled triangle. T. punctus sp. nov. Filled circle. T. acuminatus sp. nov. Crossed circle. T. acuminatus sp. nov., T. dorsalis sp. nov. Crossed square. T. acuminatus sp. nov. T. retusus sp. nov. Open circle. T. retusus sp. nov. Open triangle. T. baenzigeri Golovatch & Enghoff, 1993. Filled square. T. hongkhraiensis sp. nov. Open diamond. T. thunghaihin sp. nov. Inverted filled triangle. T. flavolineatus sp. nov. Open square. T. moniliformis sp. nov.