Inachus leptochirus Leach 1817

Inachus leptochirus Leach, 1817

Inachus leptochirus Leach, 1817, in 1815–1875, pl. 22B.—A. Milne Edwards and Bouvier, 1894:7 [Azores]; 1899:45 [key]; 1900:145 [part; Spain; Azores; Mauritania].—Doflein, 1904:73 [Seine Seamount].—Bouvier, 1922:79, pl. 2: fig. 5 [color] [Josephine Seamount; Princesse Alice Bank; S of Almadena].—Balss, 1922:72 [listed].—Monod, 1933b:503 [p. 48 on separate] [listed].—Chapman and Santler, 1955:376 [Azores].—Maurin, 1968b:484 [Spanish Sahara].—Zariquiey Alvarez, 1968:472, fig. 157a,b [Spain; references].—Christiansen, 1969:104, fig. 43, map 36 [North Atlantic].—Türkay, 1976a:26 [listed], 40, fig. 35 [Morocco].

SYNONYM.—Inachus affinis Rizza, 1839.

DISTRIBUTION.—Eastern Atlantic, from the Hebrides southward to Mauritania, including the Azores; Mediterranean. Sublittoral, from about 30 m to more than 500 m.

*Inachus nanus, new species

Inachus dorsettensis.—Monod, 1956:526, 632, figs. 715–722 [?part].—Rossignol, 1957:116 [key]. [Not Inachus dorsettensis (Pennant, 1777).]

MATERIAL EXAMINED.—Pillsbury Material: Liberia: Sta 68, 70 m, broken shell, 3, 2 ov (L). Sta 69, 29 m, coral or rock, 1 (W).

Ivory Coast: Sta 42, 62–75 m, mud with brown, branched Foraminifera, 1 (holotype), 4 ov (L). Sta 49, 73–77 m, 1 (W). Sta 60, 79–82 m, coral or rock, 1, 2 ov (L). Sta 64, 68 m, 1, 1 ov (W).

Ghana: Sta 16, 46 m, mud with Foraminifera, shells, 1, 1 ov (W). Sta 22, 51 m, rough bottom, 1, 2 ov (L). Sta 23, 42 m, foliate brown to orange bryozoans, 2, 1 ov (L). Sta 29, 58–60 m, 1 (W).

Nigeria: Sta 239, 73 m, 1 (W).

Cameroon: Sta 260, 46 m, 6, 1 ov (L).

DESCRIPTION.—Carapace (Figure 75a) with length and width subequal or length greater. Gastric region of carapace with transverse row of 4 tubercles anterior to erect gastric spine. Cardiac region with sharp, erect dorsal spine. Branchial regions each with dorsal spine, and, anterior to each, 1 blunt tubercle. Surface, anterior to branchial area, with 3–5 large tubercles, lateral margins of branchial regions irregularly tuberculate. Hepatic regions each with prominent lateral tubercle, margins irregularly tuberculate. Rostrum (Figure 75a,b) very short, margins tuberculate, outer margins convergent anteriorly. Interantennular spine acute but small, not visible in dorsal view between rostral teeth (Figure 74a). Eyes large, cornea extending laterally beyond prominent postocular spine. Posterolateral border of carapace continuous with free epimeral margin. Basal antennal segment (Figure 75b) with row of tubercles mesially and laterally, with larger spinule anterolaterally.

Chelipeds enlarged in males, about 1.3–1.4 times as long as carapace, merus and propodus markedly inflated (at cl 8.5 mm), extending with half the carpus beyond front. Chelipeds in females slenderer than in males, about 1.1 times as long as carapace, carpus not extending to front. Chelipeds in both sexes with lower margin of merus and inner border of carpus very spiny. Palm tuberculate in both sexes, length about 1.7 times height in females, 1.3–1.4 times greatest height in males. Dactylus of chela with 2 rounded teeth proximally on cutting edge in males.

Second pereiopod about 4 times carapace length in males, about 3.5 times carapace length in females (most second pereiopods detached); dactylus with minute tubercles ventrally, shorter than propodus, latter slightly shorter than merus. Dactylus of third pereiopod not overreaching propodus of second. Second to fifth pereiopods decreasing in size posteriorly, fifth about twice as long as carapace in males, about 1.5 times as long as carapace in females. Dactylus of fifth pereiopod curved but not strongly falcate, with 1 or 2 large, subdistal spinules flanked proximally by line of smaller spinules and tubercles.

Terminal somite of male abdomen rounded apically. Male pleopod as shown (Figure 75e).

MEASUREMENTS.—Carapace lengths of males 4.9 to 8.9 mm, of ovigerous females 4.8 to 8.3 mm.

DISTRIBUTION.—Inachus nanus is a sublittoral West African species, known from a few localities between Senegal and Gabon. The following records are all from Monod (1956):

Senegal: S of Cap Vert, 97–98 m; Fosse de Kayar, 100 m; S of Fosse de Kayar, 50 m; SE of Île de la Madeleine, Dakar, 48 m; off Gorée, 95, 96, and 132 m.

Sierra Leone: No specific locality, 118 m.

Gabon: Libreville, 60 m.

It has not previously been recorded from Liberia, Ivory Coast, Ghana, Nigeria, or Cameroon, but all of these lie within its known range.