Trionectes mariei ( Guinot, 1957 )

Trionectes mariei ( Guinot, 1957) View in CoL

( Fig. 3 View Fig )

Portunus (Hellenus) mariei Guinot, 1957, p. 476 View in CoL , figs. 1–2, 5–7. — Takeda & Hayashi, 1973, p. 71, pl. 1 fig. D. — Marumura & Kosaka, 2003, p. 42.

Portunus mariei View in CoL : Crosnier, 1962, pp. 43 (in key), 61, figs. 103–106. — Stephenson, 1972, pp. 14 (in key), 40 (in list). — Crosnier & Thomassin, 1974, p. 1106, fig. 5a–b.

Portunus (Xiphonectes) mariei View in CoL : Ng et al., 2008, p. 166 (in list).

Trionectes mariei View in CoL : Koch et al., 2022, p. 37 (in list).

Material examined. Ose-zaki, Suruga Bay, 6 m depth, 1 Ə (cb including epibranchial teeth of both sides, 41.5 mm, cl including frontal tooth, 18.1 mm), NSMT-32426, 25-XI-2023, coll. H. Takakura.

Remarks. Marumua and Kosaka (2003) recorded a female of Portunus (Hellenus) mariei from Kayama-jima Island, the Ryukyu Islands, without mention about the specimen itself and the distributional information in Japanese waters. In the present male specimen from Suruga Bay, both of the frontal lateral teeth of the carapace are broken off just like the holotype specimen ( Fig. 3A–B View Fig ), but all the distinguishing characters agree well with the original description and additional notes and figures of this species by Crosnier (1962) and Crosnier and Thomassin (1974).

The general shape of the carapace ( Fig. 3A View Fig ) is typical for the Portunus s.l. species, but differen- tiated in having the remarkably long epibranchial spine and eight sharp anterolateral teeth including the external orbital tooth, and the protogastric, mesogastric, cardiac and intestinal regions each with two bosses arranged side by side. Of eight carapace anterolateral teeth, fourth and sixth teeth are apparently smaller than the others. Each lateral end of the carapace posterior margin is more or less lobate and rather angulated, but not tuberculated. The third maxilliped is as repre- sented in Fig. 3B View Fig , with the merus outer part strongly produced forwards as an elongate lobe. The male pleon and first gonopod in situ are as in Fig. 3C–D View Fig , respectively. In the male pleon ( Fig. 3C View Fig ), the lateral margins of the penultimate pleonite are weakly concave at about distal one-third, and the telson is somewhat elongate and rounded along the distal margin. The male first gonopod ( Fig. 3D View Fig ) is stout, strongly curved, and not so long.

Distribution. Mayotte Island, Comoro Islands in the Mozambique Channel; Nosy Be, Madagascar (intertidal zone); Palau Islands; Kayama-jima Island, Ryukyu Islands, and Sugura Bay (6 m depth), Japan.