Olive Snapping Shrimp

Alpheus bellimanus Lockington, 1877

Alpheus bellimanus Lockington, 1877b:34; 1878:470.—Kingsley, 1878a:199; 1878c:59; 1883:111; 1899:716.—Bate, 1888:54.—Sharp, 1893:112.—Coutière, 1899:28.—Holmes, 1900:184, pl.2: fig. 41.—Rathbun, 1904:108.—Word and Charwat, 1976:42.—Luke, 1977:4.—Brusca, 1980:252.—Wicksten, 1983:41; 1984:189.

Crangon bellimanus.—Schmitt, 1921:75, fig. 51.—Chace, 1937:118.

MATERIAL EXAMINED.—Mexico: Puerto Refugio, Angel de la Guardia, Baja California (sta 704–37: 1); off San Francisquito Bay, Baja California (sta 529–36: 1 , 1 spec, sta 533–36: 2 , sta 534–36: 1 ); San Gabriel Bay, Espiritu Santo Island, Baja California (sta 633–37: 1 , 1 , 1 ovig); Agua Verde Bay, Baja California (sta 521–36: 1 , sta 662–37: 2 , sta 663–37: 1 ovig); South of Isla Partida, Baja California (sta 561–36: 1 ); Angeles Bay, Baja California (sta 702–37: 2 , 1 ); San Lorenze Channel, Espiritu Santo Island, Baja California (sta 607–36: 1 , 1 ovig); San Francisco Island, Baja California (sta 647–37: 2 ); Ensenada de los Muertos, Baja California (sta 628–37: 1 juv); South of San Marees Island, Baja California (sta 582–36: 1 ); Isabel Island (sta 277–34: 1 spec); Sulphur Bay, Clarion Island (sta 134–34: 1 spec); Isabel Island, Sinaloa (sta 747–37: 1 ).

Panama: Bahia Honda (sta 113–33; 1 juv); Secas Isle (sta 448–35: 1 , sta 450–35: 6 , 2 , 3 ovig, sta 457–35: 2 , sta 458–35: 1 juv). Perlas Islands (Pocillopora coral): 2 ovig, 12–13 Jun 1973, coll. by W. Patton, and G. Glamm.

Colombia: Octavia Bay (sta 432–35: 1 juv); Gorgona Island (sta 409–35: 2 ).

Galapagos Islands: Charles Island (sta 57–33: 1 , 3 juv, sta 166–34: 1 , 1 , sta 196–34: 1 juv); Post Office Bay, Charles Island (sta 167–34: 1 , 1 ovig, 2 juv, 2 spec, sta 193–34: 1 juv); Sullivan Bay, James Island (sta 177–34: 1 , 1 juv, sta 795–38: 1 ); Barrington Island (sta 46–33: 1 juv, 1 spec, sta 47–33: 1 juv, sta 811–38: 1 , sta 811a-38: 1 , 1 ); Academy Bay, Indefatigable Island (sta 169–34: 1 ); Conway Bay, Indefatigable Island (sta 82–33: 1 ); Cartago Bay, Albemarle Island (sta 73–33: 1 ).

MEASUREMENTS.—Males, cl 4.0–14.1 mm; females, cl 3.5–8.5 mm; ovigerous females, cl 4.5–7.9 mm.

DESCRIPTION.—Rostrum (Figure 5a,b) long, narrowly triangular, not clearly carinate posteriorly and far overreaching middle of visible part of first antennular segment; tip slightly directing upward.

Ocular hood produced anteriorly, separated from rostrum by almost indistinct dorsal depression near base of rostrum and armed with sharp tooth directing slightly inward and downward. Ocular tooth reaching to distal 0.3 of rostrum. Anterior inner margin of ocular hood slanting anteriorly from base of rostrum to ocular tooth.

Antennules slender. First antennular segment with deep, triangular carina extending from ventral inner margin; ventral part of carina ending in very minute spine directing forward (Figure 5c). Second segment slender, about 2.5 times as long as broad, 1.3 times as long as visible part of first segment and 1.5 times as long as third segment. Stylocerite narrowing to long sharp point, almost reaching to distal margin of first segment.

Scaphocerite slightly more than 3 times as long as broad. Lateral margin concave at middle. Distal spine slightly directing inward, overreaching distal end of antennular peduncle and almost reaching to distal end of carpocerite. Inner blade narrow distally, reaching to middle of distal spine. Cleft between inner blade and distal spine moderate, arising from distal 0.3 of scaphocerite.

Carpocerite overreaching distal end of antennular peduncle by length of third antennular segment. Basicerite with sharp lateral spine; spine broad at base.

Third maxilliped (Figure 5d) slender, reaching to, or slightly overreaching distal end of carpocerite. Ultimate segment tapering distally with sparse setae on distal margin, about 1.5 times as long as penultimate. Penultimate segment rather elongate, about 2.5 times as long as broad near distal end. Exopod fairly overreaching distal end of antepenultimate segment. Precoxa with one arthrobranch near distal end but with no supplementary arthrobranch.

Major first pereopod (Figure 5e,f) overreaching distal end of carpocerite by most part of chela. Major chela slightly tapering distally, about 2.9 times as long as broad, with fingers occupying distal 0.3. Movable finger opening and closing in obliquely horizontal plane, shallowly arched along proximal of superior margin and then regularly arched distally, tip broad, bulbous and overreaching tip of immovable finger. Immovable finger with tip slightly deflexed downward and outward. Palm with superior and inferior transverse grooves. Superior transverse groove deep, connecting to very slight, short round depression on inner palmar face and connecting to long longitudinal groove (superior groove), groove spreading from proximal of superior margin of palm and leading to dactylar articulation on outer palmar face; proximal shoulder well produced distally. Superior crest distal to transverse groove terminating distally in strong tooth flanking dactylar articulation; tip directing downward. Ridge to palmar plaque on outer palmar face demarked on inferior side by distinct longitudinal groove (palmar groove), groove reaching proximally to midlength of palm. Inferior crest rounded on surface and terminating in acute tooth flanking dactylar articulation. Inferior transverse groove deep, broad, connecting to very shallow longitudinal depression proximal to groove and connecting to deep, broad longitudinal depression (inferior groove) distal to groove on outer palmar face and spreading to short depression proximal to groove on inner palmar face; proximal shoulder slightly produced distally; inferior margin distal to groove fairly sinuous. Merus about 2.5 times as long as broad; inferior inner margin bearing 6 to 10 small movable spines and strong, acute immovable spine at distal end; superior margin projected as blunt tooth distally. Ischium bearing 3 to 4 small movable spines on inferior inner margin.

Minor chela of first pereopods (Figure 5g,h) about 3.6 times as long as broad, with fingers occupying distal 0.45 in male. Palmar sculpturing same as that of major chela, but less distinct. Movable finger working at horizontal direction, laterally compressed and forming lamellar expansion; inferior margin concave proximally. Immovable finger slightly deflexed downward and with superior margin broadened proximally. Movable finger and superior margin of immovable finger bearing long scattered setae on inner faces. Merus about 2.9 times as long as broad with inferior inner margin bearing 6 to 7 movable spines and strong, acute immovable spine at distal end. Ischium bearing 2 to 3 movable spines on inferior inner margin.

Second pereopod (Figure 5i) very slender, overreaching distal end of carpocerite beyond distal part of merus. Fingers of chela about 1.3 times as long as palm. First segment of carpus about 1.9 times as long as second; second segment 1.8 times as long as third; third segment slightly shorter than fourth; fifth segment slightly shorter than second and 1.6 times as long as third.

Third pereopod (Figure 5j) rather slender. Dactylus conical, slightly deflexed downward with very small tooth on distal of superior margin. Propodus about 2.5 times as long as dactylus and 1.4 times as long as carpus, with 7 movable spines and 2 or 3 irregular adjacent movable spines on inferior margin and pair at distal end; distalmost spine long, reaching to middle of dactylus. Carpus with superior distal margin produced as tooth-like process. Merus very slender, slightly less than 8 times as long as broad and 1.8 times as long as carpus. Ischium with rather strong movable spine.

Fourth pereopod almost same as third pereopod. Ischium with rather strong movable spine.

Ischium of fifth pereopod with movable spine.

Pleura (Figure 5k) of first four abdominal somites broadly rounded in both sexes. Pleuron of fifth somite subrectangular on posterior ventral margin. Abdominal sternite with no spine at midline. Appendix masculina reaching to or slightly overreaching distal end of appendix interna.

Telson (Figure 5l) slender, about 1.7 times as long as broad at anterior end, bearing two pairs of dorsal spines and with no distinct longitudinal median depression on dorsal surface. Lateral margin slightly produced at middle. Posterior margin shallowly triangular, armed with pair of spines on each lateral end, inner spine very strong, more than 3 times as long as outer one.

Uropodal endopod bearing conspicuous small spines on distal margin, laterally more strong and with inner depression at anterior half almost invisible. Uropodal exopod bearing slender movable spine flanked laterally by acute immovable tooth and internally by acutely triangular immovable tooth; movable spine reaching to distal margin of uropodal exopod; transverse suture forming two convex lobes.

VARIATIONS.—This species shows several variations. The movable finger of minor chela is typically laminate in males. In females (Figure 5m), the shape of movable finger varies from the very slightly laminated form to the fully laminated form like a typical movable finger of male. This variation has no consistent trends in relation to size because the fully laminated movable finger is observed even in very small specimens. The other prominent variation is observed in the protopodite of pleopod (Figure 5n). Some specimens have the spine-like, stout short setae (color, brown in preserved specimens) on lateral margins of the protopodites of pleopods. This variation also has no consistent trends in relation to sex and size. A. bellimanus has a spine on the ischium of the fifth pereopod, and shows that the carpocerite and scaphocerite slightly overreach the distal end of antennular peduncle. But one specimen has no spine on the ischium of the fifth pereopod and one specimen shows that the carpocerite and scaphocerite do not overreach the distal end of antennular peduncle.

HABITAT.—Lowest intertidal zone to 300 m, usually dredged on sand rocks, soft mud, fine gravel or among corallines.

COLOR IN LIFE.—Mostly olive green, orange at tip of tail fan; tips of chelae and branchial regions orange; white mark on palm of major chela (Wicksten, 1983:42).

TYPE-LOCALITY.—San Diego, California.

DISTRIBUTION.—Monterey, California south along outer coast of Baja California, southern Gulf of California, Islas Socorro and Clarion; western Mexico; Panama. Chile (Coutière, 1899:29). Now reported from Colombia and Galapagos Islands.