Tylopus dorsalis, 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 : 22-25

Tylopus dorsalis sp. nov.

urn:lsid:zoobank.org:act:EDC8D353-BE43-4D79-8BA4-E23D0FD57CE7

Figs 16 – 17 , 26

Diagnosis

The live coloration is similar to that of T. trigonum , but the new species differs in the head and collum being light brown (versus blackish), and the pattern not contrasting (versus contrasting); the gonopod structure is similar to that of T. crassipes Golovatch, 1984 , but the new species differs in process x being longer and its tip rounded dorsally.

Etymology

To emphasize process x on the solenophore arising dorsally; adjective.

Material examined

Holotype

LAOS: Ƌ, Phuthalang forest protected area, Boun Neua , Phongsali, 21°37'30" N, 101°55'55" E, ca 1125 m a.s.l., 16 Oct. 2014, leg. C. Sutcharit & R. Srisonchai ( CUMZ).

Paratype

LAOS: 1 ♀, same data as for holotype ( CUMZ).

Description

MEASUREMENTS AND COLOUR. Length 22.1 (Ƌ) or 22.3 mm (♀), width of midbody pro- and metazonae 2.5 and 3.6 mm (Ƌ) or 1.97 and 2.55 mm (♀), respectively. Live coloration light brown ( Fig. 16A ); paraterga, legs and epiproct light yellow-brown, head and collum light brown, antennomere 7 blackish, collum and following terga each with a light brown triangle and a dark brown collar covering both pro- and metazonae. Coloration of alcohol material faded after one year of preservation to light brown, with a pattern of a dark brown band in pre-sulcus area on metazonae and a pair of paramedian, longitudinal, brown stripes dorsally both on pro- and metaterga; paraterga light red-brown, head brown, antennae, legs, venter and epiproct light yellow-brown ( Fig. 16 B–J).

HEAD. Clypeolabral region densely, vertex sparsely, setose; epicranial suture distinct. Antennae rather short ( Fig. 16A ), extending behind body segment 3 (Ƌ) or 2 (♀) when stretched dorsally. In width, head <segment 3 <2 = 4 <collum <segments 5–17 (Ƌ, ♀); thereafter body gently and gradually tapering. Collum with three transverse rows of setae: 3+3 anterior, 1+1 intermediate and 2+2 posterior; a small lateral denticle at about anterior 1/3 ( Fig. 16B, D ); caudal corner of paraterga very broadly rounded, declined ventrad, not surpassing rear tergal margin.

BODY. Tegument smooth and shining, prozonae finely shagreened, metaterga smooth and leathery, posterior halves rugulose, surface below paraterga microgranulate ( Fig. 16 B–F, H). Postcollum metaterga with two transverse rows of setae: 2+ 2 in anterior (pre-sulcus) row, also 2+ 2 in posterior (post-sulcus) one. Tergal setae long, strong, slender, about 2/3 of metatergal length.Axial line traceable both on pro- and metazonae. Paraterga well-developed ( Fig. 16B, D, F ), especially so in Ƌ, set rather high (at upper 1/3 of body height), anterior edge rounded and narrowly bordered, fused to callus; caudal corner very narrowly rounded, extending increasingly behind rear tergal margin, posterior edge slightly oblique. Calluses on paraterga delimited by a sulcus only dorsally. Paratega 2 broad, anterior edge angular, lateral edge with three evident incisions. Lateral edge of following paraterga with a clear incision in anterior 1/3 ( Fig. 16B, D ). Paraterga 14–19 with caudal corner extending increasingly behind, with tip evidently curved mesad ( Fig. 16F ). Ozopores distinct, lateral, lying in an ovoid groove at about 1/3 of metatergal length in front of posterior edge of metaterga. Transverse sulcus usually distinct ( Fig. 16B, D, F ), slightly incomplete on segment 3, complete on segments 4–18, narrow, line-shaped, deep, not reaching bases of paraterga, beaded at bottom. Stricture between pro- and metazona evident, wide, rather deep, clearly ribbed at bottom down to base of paraterga ( Fig. 16B, D – G ). Pleurosternal carinae complete crests with a sharp caudal tooth on segments 2–7, reduced and remaining only a sharp caudal tooth on segment 8, reduced to a small, delicately denticulate, caudal crest on segments 9–15, retained as a minute tooth on segment 16, thereafter missing (Ƌ), or with complete crests and a sharp caudal tooth on segments 2–4, remaining only an evident caudal tooth on segments 5–12, a rounded caudal crest on segments 13–17, thereafter missing (♀) ( Fig. 16C, E, H ). Epiproct ( Fig. 16 E–G) conical, flattened dorsoventrally, with two evident, rounded, apical papillae; tip subtruncate; lateral pre-apical papillae evident, lying close to tip. Hypoproct roundly subtriangular, setigerous knobs at caudal edge small and well-separated ( Fig. 16G ).

STERNA. Separsely setose, without modifications; cross-impressions shallow; an entire, linguiform, sternal lobe between Ƌ coxae 4 ( Fig. 16I – J ). Legs long and slender, midbody ones ca 1.3–1.4 (Ƌ) or 0.9–1.1 (♀) as long as body height; Ƌ femora 6 bulged and microtuberculate ventrally ( Fig. 17E ); Ƌ femora 7 also bulged ventrally ( Fig. 17F ), but following femora not swollen; legs of segments 7–16 each with femur, postfemur, tibia and tarsus carrying a small adenostyle (tubercle) medially ( Fig. 17G ), telopodites particularly densely setose ventrally ( Fig. 17G ), tarsal brushes present until Ƌ segment 6.

GONOPOD. Rather simple ( Fig. 17 A–D); 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 rather high, directed anterodorsally, flattened, tip rounded; solenophore (sph) rather slender, strongly coiled, flattened and evidently bifid, with process x being slim and directed dorsally.

Figures

Fig. 16. Tylopus dorsalis 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. 17. Tylopus dorsalis sp. nov., holotype, Ƌ. A–D. Right gonopod, lateral, mesal, caudal and oral views, respectively. Scale bars = 0.2 mm. Abbreviations are explained in the text.

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.