Ligidium deltodontum, Li, 2017

Li, Wei-Chun, 2017, Morphology and molecules reveal high species diversity of Ligidium (Crustacea: Oniscidea: Ligiidae) in Jiangxi, China, Zoological Journal of the Linnean Society 179 (3), pp. 627-641 : 636-637

LIGIDIUM DELTODONTUM SP. NOV. ( FIGS 2 , 3)

Diagnosis

Unique in characters of the male pleopod 2 endopod: the subapical part has a thumb-shaped process on outer margin, and the apical tip has a triangular tooth-like process.

Description

Body length of males 8.0 mm, of females 9.0 – 10.0 mm. Body elongated (c. two times as long as wide); pereonites 1 and 2 without ‘bristle field’ on posterior margin of epimera. Colour in alcohol dark grey with white spots on dorsal surface.

Antennule ( Fig. 2A ): First article broadened towards three distal setae at the tip; second article about 1.5 times as long as the first, ending with three distal setae; third article with two small setae at apical tip.

Antenna ( Fig. 2B ): Third article of peduncle with seta near distal tip; fourth article bears three distal setae; fifth article equipped with two setae; flagellum composed of 13 articles.

Mandibles ( Fig. 2C, D ): Left mandible with three-toothed incisor; lacinia mobilis three-toothed; three penicils between lacinia mobilis and molar process. Right mandible with three-toothed incisor; lacinia mobilis single-toothed; two penicils between lacinia mobilis and molar process.

Maxillule ( Fig. 2E ): Inner lobe with three stout penicils and long seta near distal margin; outer lobe with six apical teeth.

Maxilla ( Fig. 2F ): Distally divided into two parts with blunted rounded apices; large lappet covered with tiny spines near distal margin and two elongated setose penicils near lateral margin at subapical part.

Maxilliped ( Fig. 3A): Endite rectangular, distal margin with tooth at inner distal angle; palp with four setae on outer margin.

Telson ( Fig. 3B): Distal margin distinctly convex in the middle, gently concave near lateral margin and forming blunted rounded corners.

Uropod ( Fig. 3B): Uropodal protopod about three times as long as broad; inner-distal projection of protopod slightly longer than width of its base; endopod about twice as long as exopod, ending with long seta; exopodal tip with a cluster of small setae.

Male – pereopods ( Fig. 3C, D): Pereopod 1 basis with three setae at both the inner and outer margins; ischium concave on outer margin, bears two small setae on inner margin; merus with seven setae on inner margin and two setae at outer distal angle; carpus with five setae on inner margin; propodus bears several small setae on inner margin and single small seta at outer distal tip. Pereopod 7 basis bears several tiny spines near base and single distal seta on inner margin; ischium narrow basally, broadened towards subtip, then narrowed towards distal tip, bears three setae on inner margin; merus with five long setae on inner margin and two setae at outer distal angle; carpus bears five long setae on inner margin and three setae at outer distal angle; propodus bears three small setae on inner margin.

Male – pleopods ( Fig. 3E–I): Pleopod 1 exopod with rounded distal margin, endopod with triangular projection. Pleopod 2 exopod broad bean-shaped, distinctly concave at base; endopod long and thin; distal part thumb-shaped and concave on inner margin, outer margin with thumb-shaped process, apical tip with tooth-like process, pointing to base.

Holotype

Male: China, Jiangxi Province, Jingdezhen, Fuliang (29 ° 26 0 N, 117 ° 15 0 E), Huangzihao , c. 600 m a.s.l., 26.v.2012, W. Li leg. (= collector), DNA no. L14114 ( Fig. 1 ).

Paratypes

One male and five females, same data as the holotype, DNA no. L14115 ( Fig. 1 ) .

Distribution and habitat

This species is only known from Jiangxi Province, China. The type locality is nearby a stream on the mountain slope in a secondary forest .

Etymology

From the Latin deltodontus (= triangular tooth-like), referring to the male endopod of pleopod 2 with a triangular process at apical tip.

Figures

Figure 1. Maximum likelihood tree obtained from the phylogenetic analysis of concatenated 12S and 16S rRNA sequences; values given above the nodes of branches are bootstrap supports for each node. The scale bar represents the number of substitutions per site. The tree is unrooted. Abbreviation: L., Ligidium.

Figure 2. Ligidium deltodontum sp. nov., holotype; A–D, dorsal view; E–F, ventral view. A, antennule; B, antenna; C, left mandible; D, right mandible; E, maxillule; F, maxilla.