Mecistocephalus longichilatus Takakuwa, 1936

Published, First, 2007, The Mecistocephalidae of the Japanese and Taiwanese islands (Chilopoda: Geophilomorpha), Zootaxa 1396, pp. 1-84 : 45-47

Mecistocephalus longichilatus Takakuwa, 1936

Fig. 58

[1] Mecistocephalus longichilatus: Takakuwa 1936d — Trans. Nat. Hist. Soc. Formosa 26: 215 (original description); fig. 1–2

Mecistocephalus (Mecistocephalus) longichilatus: Takakuwa 1936b — Trans. Nat. Hist. Soc. Formosa 26: 433 (key) Formosocephalus longichilatus: Verhoeff 1937 — Bull. Raffles Mus. Singapore 13: 228

Formosocephalus longichilatus: Takakuwa 1938a — Annot. Zool. Japon. 17: 353 (also as Mecistocephalus (Mecistocephalus) longicapillatus [sic] on page 353)

[2] Formosocephalus longichilatus: Takakuwa 1940 — Fauna Nippon. 9: 90 (redescription); fig. 93–94 Formosocephalus longichilatus: Takakuwa 1943 — Bull. Biogeogr. Soc. Japan 13: 165

Mecistocephalus (Formosocephalus) longichilatus: Attems 1947 — Ann. Naturhistor. Mus. Wien 55: 102 (key) Formosocephalus longichilatus: Wang & Mauriès 1996 — Mém. Mus. natn. Hist. Nat. Paris 169: 88 Mecistocephalus longichilatus: Bonato et al. 2003 — Syst. Entom. 28: 550, 551

Diagnosis. A Mecistocephalus species with 49 leg­bearing segments. Body length reaching at least 2 cm. Trunk without dark patches. Head 1.8 times as long as wide. Areolate part of the clypeus without smooth insulae, each side with 3 setae; clypeal ratio about 3.0. Anterior ala of the labrum subtriangular, with the medial margin reduced to a vertex. Medial projections and telopodites of the first maxillae extremely elongated, about 6.5 times as long as wide and reaching the first antennal article.

Type material. Syntypes: number, sex and age not stated; reaching at least 20 mm ( Takakuwa, 1936d).

Type localities. ‘ Karenko , Giran , Daito, Gyokusei’, Taiwan ( Takakuwa, 1936d) .

Depository of type material. The syntypes are probably lost (see Discussion).

Material examined. None.

Description. Body size reaching at least 2 cm. Body colour yellow, without dark patches; head and forcipular segment darker. Head 1.8 times as long as wide. Clypeus: clypeal ratio about 3.0; areolate part without smooth insulae; a limited area with relatively small scutes on each side, close to the medial line, bearing 3 setae close to each other; plagulae without evident sensilla or setae. Labrum: anterior ala subtriangular, the medial margin reduced to a vertex, internal margins of side­pieces quite parallel. Spiculum present, distinctly curved inwards; buccae with two setae on the posterior half only. Mandible: about 4 lamellae; each well developed lamella with about 5 teeth. First maxillae: anterior corners of coxosternum not projecting; each medial projection about 6.5 times as long as wide, reaching the anterior margin of the first antennal article, straight, attenuated at the apex, with waved margins (particularly the internal one); telopodites similar to the medial projections in size and shape. Second maxillae: article I of telopodite about 3.2 times as long as wide, with a spiniform process on the external side, at the distal end; article III about 2.3 times as long as wide, attenuate, apical claw slender. Forcipules: article I with two rudimentary teeth; articles II and III with a tooth each. A total of 49 leg­bearing segments. Sternal sulcus apparently not furcate.

Distribution in the considered area.

Taiwan: ‘Karenko, Giran, Daito, Gyokusei’ [1] (type localities); Huolian­gang (Huolian­xian), Yilan (Yilan­xian), Taidong (Taidong­xian) and Yujing (Tainan­xian) [2] (transcribed from Japanese) (see remarks) .

General distribution. Taiwan.

Remarks. Among known mecistocephalids M. longichilatus is unique for the elongation of the appendages of the first maxillae ( Fig. 58). Verhoeff (1937) proposed for this species the genus Formosocephalus , which was considered either as a genus or as a subgenus by following authors and has remained, to date, monospecific. According to the original description, Formosocephalus Verhoeff, 1937 is distinct from Mecistocephalus Newport, 1843 only for the elongation of the appendages of the maxillae I, apart from other minor putatively peculiar traits, namely the presence of a projection on the article I of the telopodite of the second maxille and the shape of the spiculum, which is evidently curved inwards and very sharp. However, a cladistic analysis of mecistocephalids suggested that ‘ Formosocephalus’ longichilatus is nested well within the wide radiation of the genus Mecistocephalus , thus representing a derived condition inside this group ( Bonato et al., 2003). Pending the examination of new specimens of M. longichilatus and an evaluation of the possible paraphyletic condition of the remaining Mecistocephalus species , we do not use Formosocephalus as a valid taxon.

As for the distribution, localities given by Takakuwa (1940) most probably correspond to the localities of the type series, though cited in a different way.