Sesarma bidentatum Benedict 1892

Sesarma bidentatum Benedict, 1892

Sesarma bidentata Benedict, 1892:77.—Jarvis, 1897.—Rathbun, 1897c:33.

Sesarma-like.—Andrews, 1892:72.

Sesarma (Sesarma s.s.) bidentata.—Tesch, 1917:135.

Sesarma (Sesarma) bidentatum.—Rathbun, 1918:295, pl. 80.

Sesarma bidentatum.—Hartnoll, 1964b:159; 1965:113; 1971:260.—Abele and Means, 1977:91—Gutnol, 1988, 1988:8, fig. 1A.

MATERIAL EXAMINED.—Jamaica: St. Thomas Parish, stream adjacent to Bath Fountain Spa, elevation 135 m, l1, 10, 3 May 1976, L. Abele, B. Means; Portland Parish, 2.6 miles [4.2 km] W, SW of Ecclesdown on Project Road, Drivers River drainage, 650 m elevation, 12 4, 1 ovigerous , 5 May 1976, L. Abele, B. Means; Mabess River, N slope of Blue Mountains, 1, 21 July 1926, USNM 71170; same locality, 1932, W.G. Lynn, MCZ 12170; Mabess River above falls, 1, 2, 1932, W.G. Lynn, USNM 74849; Stony Valley River, 1, 20 Jun 1928, C.R. Orcutt, USNM 15539; tributary of Clyde River near Chester Vale House, 1, 1, 18 Jun 1936, W. Gardner Lynn, USNM 72772; Clyde River near Clydesdale, 1, 1, 28 Sep 1932, W.G. Lynn, USNM 74494; Clyde Spring, Blue Mountains, 5, 10, C.B. Wilson, USNM 42889; Clyde Spring near Cincliona, elevation 1300 m, 10 June 1910, USNM 41752; Clyde Spring, 1, 1, C.B. Wilson, MCZ 12169; St. Andrew Parish, near Kingston Harbor, 1 (holotype), T.H. Morgan, USNM 17281; Mountain Spring, 1, P.W. Jarvis, USNM 19053; Hardware Gap probably tributary of Buff Bay River, 1, 1 Jul 1932, W.R. Hatch, USNM 74825; St. Mary Parish, Lucky Hill Cooperative Farm, in stream inside cave, 400 m elevation, 3, 1, 6 May 1976, L. Abele, B. Means; Manchester Parish, Mandeville, 3, Henderson and Simpson, USNM 18573; St. Elizabeth Parish, Accompong, 1 P.W. Jarvis, USNM 19052; Trelawny Parish, small stream near Troy, elevation 1650 m, 4 1, Nov 1905, W. Harris, USNM 32285.

DESCRIPTION.—Carapace broader than long (cl/cb = 0.834±0.023 in males, 0.882±0.057 in females), widening posteriorly. Outer orbital angle acute, lateral margin convex to strong anterolateral tooth. About nine transverse striae on lateral surface of carapace. Interorbital region subdivided into four lobes. Frontal region with margins subparallel, concave medially; iw/cb = 0.469±0.03 in males, 0.470±0.04 in females. Dorsal surface of carapace smooth; a few scattered setae on lateral surfaces.

Eyes well developed, pigmented.

Male chelipeds large, robust; merus with posteromedial margin granulate with a subdistal lobe, anteromedial margin with teeth, expanded subdistally; two rows of setae on medial surface. Carpus with granules becoming acute on anteromedial margin. Chelae swollen, granular with a few large acute granules on medial surface; dorsal surface with poorly defined row of granules ending in an acute granule; immovable finger with about seven large teeth; corneous tip asymmetrically bifid. Movable finger with about 10 to 12 small acute tubercles in poorly defined row; corneous tip acute. Female chelipeds similar though much less robust, lacking acute granules and carpus with tuft of setae on medioproximal angle.

Walking legs relatively long; m1/mw of third variable increasing to about 3.0 in large individuals. Dactyli with three dorsal and three ventral rows of pubescence; middle of ventral rows widest in males whereas ventral rows poorly defined in females. Propodus with dorsal pubescence, propodi of walking legs 1 and 2 with distinct ventral pubescence present on mature males, weak on large females; propodi of remaining legs with about five stout dark spines evenly spaced on inferior margin and three to six on distal margin. Dactylus slightly shorter than propodus and longer than carpus.

Male abdomen subtriangular in outline; telson length and width subequal; distal margin lined with setae. Gonopod simple, unarmed distal region curved laterally at about 30° angle.

Female abdomen subcircular, telson length and width subequal. Female gonopore concave anterolaterally, notched posteriorly, narrowing and lengthening medially, operculum somewhat rectangular.

MEASUREMENTS.—Mature males cb 20.8 to 25.8 mm; mature females cb 20.5 to 23.7 mm, ovigerous females cb 20.5 to 23.2 mm. Males below cb 20 mm are immature, whereas females below cb 18.5 are immature (see Hartnoll, 1964b).

TYPE LOCALITY.—Kingston Harbour, Jamaica (Benedict, 1892). This is probably an error, as this species is freshwater and has never been collected near the harbor (Hartnoll, 1964b).

TYPE.—The female holotype is in the National Museum of Natural History, Smithsonian Institution (USNM 17281).

DISTRIBUTION.—This species is endemic to Jamaica and has been reported from the following localities (Hartnoll, 1964b): St. Thomas Parish (Bath Fountain, 130 m; Corn Puss Gap, 800 m); Portland Parish (John Crow mountains, 300 m; Clydesdale 1000 m; Section 1300 m; Clyde Spring, 1500 m); St. Andrew Parish (Mountain Spring, Yallahs River, Way Water Hermitage, 650 m); St. Mary Parish (Lucky Hill, 400 m); Manchester Parish (Mandeville); Trelawny Parish (Troy); St. Elizabeth Parish (Accompong). Sesarma bidentatum may not occur much above 1500 m, as I collected extensively on Blue Mountain in 1976 and was unable to find the species at higher altitudes.

HABITAT.—Sesarma bidentatum occurs in freshwater rivers, streams, and deep pools from about 100 (pers. obs.) to 1500 m elevation (Hartnoll, 1964b).