Antheromorpha nguyeni, Likhitrakarn, Natdanai, I. Golovatch, Sergei, Semenyuk, Irina & Panha, Somsak, 2019

Likhitrakarn, Natdanai, I. Golovatch, Sergei, Semenyuk, Irina & Panha, Somsak, 2019, A new species and a new record of the Southeast Asian millipede genus Antheromorpha Jeekel, 1968 (Polydesmida, Paradoxosomatidae) from Vietnam, ZooKeys 832, pp. 77-89 : 79-83

Antheromorpha nguyeni sp. n. Figs 2, 3, 4

Type material.

Holotype. ♂ (ZMUM), Vietnam, Gia Lai Province, Kon Ka Kinh National Park, 14°13'08"N, 108°19'31"E, 1200 m a.s.l., tropical forest with Lithocarpus spp. abundant on hill slopes, on forest floor, daytime, 24.V.2017, leg. I Semenyuk.

Paratypes. 1 ♂ (ZMUM), same locality, together with holotype; 1 ♂ (ZMUM), same locality as holotype, but on top of a hill with cloud forest, 14°13'12"N, 108°19'54"E, 1500 m a.s.l., on log, daytime, 26.V.2017; 1 ♂ (CUMZ), same locality as holotype, broadleaved tropical forest in river valley, on log, 800 m a.s.l., 14°12'46"N, 108°18'55"E, night time 22.V.2017, all leg. I Semenyuk.

Name.

To honour Nguyen Duc Anh, the leading Vietnamese myriapologist.

Diagnosis.

Differs from congeners mainly in the colour pattern (a uniformly black-brown body with contrasting yellow-brown paraterga and epiproct), as well as in gonopod process d being unusually short, approximately half as long as the solenophore.

Description.

Length of holotype 41.5 mm, width of midbody pro- and metazonae 3.2 and 4.7 mm, respectively. Paratypes 39.5-42.5 mm long, 2.9-3.8 and 4.5-5.1 mm wide on midbody pro- and metazonae, respectively (♂).

Colouration of live animals blackish (Fig. 2A), edges of paraterga dark to light brown; antennae dark brownish, legs and venter dark to light brown (Fig. 2A); colouration in alcohol, after one-year-long preservation, faded to dark brownish (Fig. 2 B–H), edge of paraterga faded to brownish or pale brown, antennae legs and venter light brown to pale yellowish (Fig. 2 B–J).

Clypeolabral region sparsely setose; epicranial suture distinct. Antennae long (Fig. 2C), extending behind metaterga 3 when stretched dorsally (♂). In width, head <segment 4 <3 <collum <segment 2 <5 <6-17 (♂), body gently and gradually tapering thereafter. Collum with three transverse rows of setae: 3+3 in anterior, 2+2 in intermediate, and 3+3 in posterior row; paraterga very broad (Fig. 2B), slightly upturned, anterior edge angular, lateral edge smooth, caudal corner almost or fully pointed, extending behind rear tergal margin (Fig. 2B, C).

Tegument generally smooth and poorly shining, prozonae finely shagreened, metaterga leathery and rugulose (Fig. 2A, B, D, F), surface below paraterga finely microgranulate (Fig. 2C, E, H). Postcollum metaterga with two transverse rows of setae traceable at least as insertion points when setae broken off: 2+2 in anterior (pre-sulcus) and 3+3 in posterior (post-sulcus) row. Tergal setae simple, slender, ca. 1/3 of metatergal length. Axial line visible only on metazonae, starting with collum. Paraterga very strongly developed (Fig. 1 B–H), mostly clearly upturned above dorsum; only paraterga 2-4 slightly upturned, all lying below dorsum, set at ca. upper 1/3 (segments 2 and 3) or 1/4 (segment 4 and following ones) of body height, moderately enlarged in lateral view on pore-bearing segments, thinner on poreless ones; anterior edge broadly rounded and narrowly bordered, fused to callus; calluses delimited by a sulcus only dorsally on segments 2-4, following segments delimited by a sulcus both dorsally, and, albeit more poorly so, ventrally, in dorsal view narrower on poreless segments than on pore-bearing ones; lateral edge without incisions, caudal corners narrowly rounded to fully pointed, always extending behind rear tergal margin, posterior edge oblique to clearly concave, especially well so in segments 16-19 (Fig. 1B, D, F). Ozopores evident, lateral, lying in an ovoid groove at ca. 1/4 of metatergal length in front of caudal corner. Transverse sulcus usually distinct (Fig. 2B, D, F), complete on metaterga 5-18, shallow, reaching the bases of paraterga, very faintly beaded at bottom, incomplete and nearly wanting on segments 5 and 19. Stricture between pro- and metazona rather wide, deep, beaded at bottom down to base of paraterga (Fig. 2 B–D, F). Pleurosternal carinae complete crests with a sharp caudal tooth on segments 2-4, thereafter crests bulged anteriorly and with a small, sharp, caudal tooth on segments 5-7, with only a small, sharp, caudal tooth on segments 8-10, and a very small denticle on segments 11-16 (Fig. 2C, E, H). Epiproct (Fig. 2H) long, stout, conical, flattened dorsoventrally, with two evident, caudoventrally curved, apical papillae; tip subtruncate; pre-apical papillae small, but evident, lying rather close to tip. Hypoproct subtriangular, caudal margin round, setiferous knobs at caudal edge evident and clearly separated.

Sterna sparsely setose, shining, cross-impressions shallow, without modifications; but with two rounded, low, fully separated, setose cones between ♂ coxae 4 (Fig. 2I, J). A conspicuous ridge present in front of gonopod aperture. Legs moderately long and slender, midbody ones ca. 1.2-1.5 times as long as body height, prefemora without modifications, ♂ tarsal brushes present until segment 17.

Gonopods (Figs 3, 4) simple, with femorite ca. 3 times as long as prefemoral (= strongly setose) part. Femorite moderately curved caudad, postfemoral portion demarcated by an oblique lateral sulcus; solenomere flagelliform, almost fully sheathed by solenophore, tip of solenophore very deeply bifid; with a rather long, slender, fully pointed process d; process m with a narrowly rounded terminal lobule, longer than a small, rounded process v with a very small, middle, spiniform prong.

Remarks.

Adults of the new species were found in May during a short expedition to a small area within Kon Ka Kinh National Park near its headquarters. A prospected forest with a similar forest structure within the same park near the village of Krong (N14°17', E108°26', 700-1000 m a.s.l.), ca. 14 km NE of the type locality, failed to reveal this species. It co-exists at the type locality together with Orthomorpha scabra Jeekel, 1967 and three other Orthomorpha species, all apparently undescribed. According to IS’ observations, the five species share the same microhabitats. Given the conspicuously large and similar sizes of the adults of Antheromorpha and Orthomorpha , an ecological study of this syntopy in Kon Ka Kinh National Park would be worthwhile.

Although our new species is superficially very similar to Orthomorpha species such as O. elevata Likhitrakarn, Golovatch & Panha, 2011, from Perak State, Malaysia, it is clearly different in the shape of the sternal lamina between ♂ coxae 4 and in gonopodal structure ( Likhitrakarn et al. 2011).