Limnogeton expansum Montandon, 1896

Ribeiro, José Ricardo I., Meyin-A-Ebong, Solange E., Le-Gall, Philippe & Guilbert, Eric, 2014, A taxonomic synopsis of Limnogeton Mayr, 1853 (Insecta: Hemiptera: Heteroptera: Belostomatidae), Zootaxa 3779 (5), pp. 573-584 : 575

Limnogeton expansum Montandon, 1896

( Figs. 1 A–E)

Limnogeton expansum Montandon, 1896: 519 . Limnogeton expansum: Poisson (1949) : 7.

Limnogeton expansum: Linnavuori (1971) : 356.

Types. Limnogeton expansum was described based on a holotype from Tanganyika ( Democratic Republic of Congo), Africa, deposited in ISNB according to Montandon (1896).

Material examined. CONGO. Brazzaville, [“393”], [“92”], 1892, (Dybowsky), identified as L. expansum by A. L. Montandon in 1899, J. R. I. Ribeiro det. 2011: 1 f ( MNHN); Haute-Sanga, (P. A. Ferrière 106-97): 1 m ( MNHN). CAMEROON. Batouri, M. [?] de Lisle, “MUSÉUM PARIS //P. Lepesme R. Paulian//A. Villiers, 1939, ‘42’”, J. R. I. Ribeiro det. 2011, (identified as L. fieberi ): 2 m ( MNHN).

Distribution. Tanganyika ( Democratic Republic of Congo) and Kilimandjaro ( Tanzania) ( Poisson 1949; Linnavuori 1971). This species is newly recorded herein from Batouri ( Cameroon) and Brazzaville and Haute- Sanga ( Congo).

Measurements (m / f): Total length (from apex of head to apex of abdomen at rest): 50.0–57.2 / 54.1; greatest width of body: 24.0–27.2 / 26.5.

General coloration. Almost uniformly brown. Body ovate with wings covering abdomen.

Head, thorax, and abdomen. Pronotum with longitudinal median carina ( Fig. 1 A, LMC) extending only onto posterior portion; prosternal keel elongate and slightly directed anteriorly at apex, straight, robust, cylindrical, with its apex acute, slightly projecting anteriorly ( Fig. 1 B, PC). Pilosity developed, covering half of connexivum, slightly constricted between spiracles, not extending posteriorly along genital operculum ( Fig. 1 C, PIL).

Male genitalia: Parameres symmetrical, both with apex curved and poorly hooked; left one strongly edentate, the other smoothly curved; length of phallotheca about 1.4 times ventral diverticulum in dorsal view; ventral diverticulum robust; dorsal arms of phallotheca strongly divergent, symmetrical, connected or fused along basal portion, V-shaped and abruptly narrowed at apex in dorsal view ( Fig. 1 D); lateral outer margins of ventral diverticulum almost straight ( Fig. 1 E), ventral diverticulum with anterior margins broader, becoming narrow posteriorly ( Fig. 1 E).

Taxonomic notes. Males of this species can be readily distinguished from the other species of Limnogeton by having the dorsal arms of ventral diverticulum robust, V-shaped, and conspicuously acute at the apex ( Fig. 1 D).

Figures

FIGURE 1. Limnogeton expansum Montandon, external morphology and male genital structures. 1 A, Dorsal habitus showing pronotum with longitudinal median carina. 1 B, Head showing prosternal carina, lateral view. 1 C, Ventral aspect of abdomen showing development of pilosity which covers half of connexivum. 1 D – E, Male genital structures: 1 D, Dorsal apical membranous processes arising from phallotheca. 1 E, Ventral diverticulum of phallosoma showing anterior margins, ventral view. LMC, longitudinal median carina; MVD, margins of ventral diverticulum; PC, prosternal carina; PIL, pilosity of connexivum.