Smoothclaw Snapping Shrimp

Alpheus paracrinitus Miers, 1881

Alpheus paracrinitus Miers, 1881b:365, pl. 16:fig. 6.—Kingsley, 1883:123.—Osorio, 1887:230; 1889:137; 1898:194.—Coutière, 1899:34; 1905:901, pl. 82:fig. 38 [part].—Rathbun, 1900a:313.—Balss, 1916:2.—Schmitt, 1939:12.—Holthuis, 1951:74.—Chace, 1962:609; 1972:69.—A. Banner and D. Banner, 1964:92; 1966:115, fig. 41; 1967:278; 1984:42.—D. Banner and A. Banner, 1981:37.—Crosnier and Forest, 1965b:605; 1966:253, figs. 15a–f.—Pequegnat and Ray, 1974:246, figs. 49e, 51.—Miya, 1974:157, pl. 31.—Abele, 1979:275.—Carvacho, 1979:454.—Brusca, 1980:252.—Wicksten, 1983:45.

Alpheus ascensionis Ortman, 1893:45.

Alpheus paracrinitus var. bengalensis Coutière, 1905:901, pl. 82: figs. 37–37e [part].—Banner, 1956:358; 1957:204; 1958:168.

Alpheus bengalensis Holthuis, 1958:25.

Crangon paracrinitus.—Schmitt, 1939:12.

Crangon togatus Armstrong, 1940:2, fig. 1.

Crangon paracinita.—Banner, 1953:110.

Crangon paracrinita var. bengalensis.—Banner, 1953:110, fig. 40a–k.

MATERIAL EXAMINED.—Mexico: San Gabriel Bay, Espiritu Santo Island, Baja California (sta 604-36: 2 , 1 ovig, sta 634-37: 1 , 1 , 3 ovig, sta 638-37: 3 , 1 ovig); San Francisco Island, Baja California (sta 652-37: 1 ); Sulphur Bay, Clarion Island (sta 140-34: 2 , 3 , 2 ovig).

Costa Rica: Playa Blancas (sta 465-35: 1 ); Guanacaste, Playa del Coco (sta 1566: 1 ovig, 1 juv).

Panama: Secas Isle (sta 447-35: 1 ovig); Pedro Gonzales, Perlas Island (sta 33-4: 1 juv).

Galapagos Islands: Black Beach Anchorage, Charles Island (sta 33-33: 1 , 2 ovig); Albemarle Island, Cartago Bay (sta 73-33: 1 , 1 , 2 ovig); Hood Island (sta 357-35: 2 , 1 ovig); Gardner Bay, Hood Island (sta 25-33: 1 juv, sta 28-33: 3 ); South Seymour Island (sta 789-38: 1 , 1 ovig); Charles Island (sta 351-35: 1 , 2 ovig); Tower Island, Darwin Bay (sta 94-33: 1 ovig, sta 98-33: 1 ovig, sta 101-33: 1 ); Barrington Island (sta 811a-38: 2 , 1 ovig); James Island, Sullivan Bay (sta 343-35: 1 , 1 ); Academy Bay, Indefatigable Island (sta 168-34: 1 ).

MEASUREMENTS.—Males, cl 2.7–6.2 mm; females, cl 3.5–6.7 mm; ovigerous females, cl 5.1–8.1 mm.

DESCRIPTION.—Rostrum (Figure 20a,b) triangular, acute, somewhat longer than wide at base, scarcely reaching to middle of visible part of first antennular segment and bearing several short setae along lateral margins. Rostral carina slightly extending posteriorly, rounded dorsally.

Ocular hood not inflated dorsally, slightly produced anteriorly; anterior margin very convex and very concave near base of rostrum. Orbitorostral groove weak, fairly distinct just behind anterior margin near base of rostrum.

First antennular segment bearing shallowly triangular carina extending from ventral inner margin; ventral part ending in acute spine (Figure 20c). Second segment about 1.7 times as long as broad, slightly longer than visible part of first segment; first segment slightly longer than third segment. Stylocerite narrowing to long sharp point, almost reaching to distal margin of first segment.

Scaphocerite with lateral margin very slightly concave to almost straight. Distal spine directing slightly inward, scarcely reaching to distal end of antennular peduncle and falling short of distal end of carpocerite. Inner blade narrowly rounded distally, falling far short of tip of distal spine. Cleft between inner blade and distal spine arising from distal 0.3 of scaphocerite.

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

Third maxilliped (Figure 20d) slightly overreaching distal end of carpocerite. Ultimate segment slender, about 6 times as long as broad at proximal end, 2.4 times as long as penultimate, tapering distally, with long setae on superior and inferior margins as well as on distal margin; tufts of setae on inner face dense. Penultimate segment about 2 times as long as broad with scattered long setae on superior and inferior margins. Antepenultimate segment produced on superior distal margin and with sparse short setae on inferior margin. Exopod slightly overreaching distal end of antepenultimate segment. Precoxa with one arthrobranch near distal end and also with small supplementary arthrobranch near proximal end.

Major first pereopod (Figure 20e,f) overreaching distal end of carpocerite by almost length of chela. Major chela slightly compressed laterally, lacking sculpturing, about 3.1 times as long as broad with fingers occupying slightly less than distal 0.3. Movable finger shallowly arched in profile with tip blunt, slightly overreaching tip of immovable finger. Merus about 2 times as long as broad; inferior inner margin smooth, bearing one acute spine at distal end.

Minor chela of first pereopods (Figure 20g,h) about 5 times as long as broad and bearing dense long setae on inner face, especially on fingers. Fingers occupying slightly less than 0.6 length of chela. Palm with blunt tooth flanking dactylar articulation on inner face. Merus with inferior inner margin smooth, bearing spine at distal end.

Second pereopod (Figure 20i) reaching distal end of carpocerite beyond proximal part of first carpal segment. Fingers of chela about 1.3 times as long as palm. First segment of carpus about 2 times as long as second; second segment subequal to or slightly longer than fifth, about 1.7 times as long as third; third segment subequal to fourth.

Dactylus of third pereopod (Figure 20j) simple, slightly curved and elongate, about length of propodus. Propodus about 1.3 times as long as carpus and armed with 7 movable spines in irregular line on inferior margin and pair at distal end. Carpus with both superior and inferior distal margins slightly projected anteriorly but rounded. Merus about 5 times as long as broad and 2 times as long as carpus. Ischium bearing movable spine.

Fourth pereopod almost same as third pereopod. Ischium bearing movable spine.

Ischium of fifth pereopod bearing movable spine.

Pleura (Figure 20k) of abdominal somites broadly rounded. First four abdominal sternites of male with spine at midline of each sternite, but spines of third and fourth sternites less distinct; in female, abdominal sternite with no spine. Appendix masculina clearly overreaching distal end of Appendix interna.

Telson (Figure 20l) about 1.4 times as long as broad at anterior end, armed with two pairs of rather stout dorsal spines and with no distinct longitudinal median depression on dorsal surface. Posterior margin rounded, bearing indistinct seta-like spines and armed with pair of spines at each lateral end; inner spine almost 2 times as long as outer one.

Uropodal endopod bearing seta-like spines on distal margin and with inner depression at anterior half fairly distinct. Uropodal exopod bearing slender movable spine flanked laterally by very acute immovable tooth and internally by rounded lobe; movable spine not overreaching distal margin of uropodal exopod; transverse suture forming two convex lobes.

HABITAT.—Shore to 5 m; rocky, coral, and coral clump. On turtle grass and Porites flats (Chace, 1972:69).

COLOR IN LIFE.—Translucent white with bands of red on thorax and abdomen, chelae with red mottling, eggs yellow to greenish (Banner, 1953:112).

TYPE-LOCALITY.—Goree, Senegal.

DISTRIBUTION.—Pantropical. Western Atlantic, Bermuda to Tobago; Flower Garden Reefs off Texas; eastern Atlantic, West Africa; Indian Ocean; tropical Indo-West Pacific to Hawaii; eastern Pacific from Gulf of California, western Mexico, Islas Clarion, Panama, Clipperton and Galapagos Islands.

Alpheus paracrinitus Miers, 1881

Alpheus paracrinitus Miers, 1881:365, pl. 16: fig. 6 [type locality: Goree Island, Senegal].—D.M. and A.H. Banner, 1982:129, fig. 35; 1985:21.

Alpheus paracrinitus, var. Bengalensis Coutière, 1905:901, pl. 82: fig. 37 [type locality: Minicoy, Laccadive Islands].

Crangon togatus Armstrong, 1940:2, fig. 1 [type locality: La Piedra Prieta reef, Barahona, Dominican Republic].

DIAGNOSIS.—(Diadema Group). Body not unusually compressed or setose; rostrum variable, not overreaching distal margin of 1st antennular segment, carina low, rounded; carapace without median tooth or tubercle on gastric region, without paired teeth overhanging posterior ends of adrostral furrows, anterior margin unarmed, sinuous or transverse mesial to orbital hood, orbital hood unarmed, adrostral furrows shallow; 2nd antennular segment about twice as long as wide; basal antennal segment (basicerite) armed with acute ventrolateral tooth not reaching level of tip of stylocerite; antennal scale with lateral margin nearly straight, distolateral spine slightly overreaching distal margin of blade; 1st pereopods with or without tooth on inferior flexor margin of merus; major chela oval in cross section, about 3 times as long as wide, dactyl little skewed, not double-ended, palm without sculpture, slightly more than twice as long as high, fingers slightly less than as long as palm; minor chela about 4 times as long as wide, fingers slightly longer than palm, dactyl occasionally “balaeniceps” in male; 2nd pereopod with proximal carpal article little more than as long as to slightly longer than 2nd; 3rd pereopod with dactyl simple, propodus with 6–8 spines on flexor margin, carpus distally bluntly produced on both extensor and flexor margins, merus unarmed, ischium bearing small movable spine; maximum carapace length to base of rostrum about 7 mm.

RANGE.—Pantropical; intertidal to 18 meters.

Alpheus paracrinitus Miers,1881

Alpheus paracrinitus Miers, 1881a:365, pl. 16: fig. 6.—Crosnier and Forest, 1966:253, fig. 15.

Alpheus ascensionis Ortmarm, 1893:45.

MATERIAL.—Manning 1971 Collection: Sta ASC-11, English Bay: 3 females [1.7–3.3],2 ovig. [2.8–3.3], 1? [3.4].—Sta ASC-15, English Bay: 3 males [3.8–5.2], 2 females [2.2– 4.8].—Sta ASC-21, English Bay: 1 female [1.8].—Sta ASC-22, McArthur Point 1 male [2.6].—Sta ASC-23, McArthur Point 2 females [2.7–5.7], 1 ovig. [5.7].

Smithsonian 1976 Collection: Sta 3A–76, English Bay: 1 male [5.0], 1 ovig. female [5.7].—Sta 3D–76, English Bay: 2 males [3.0–3.8], 1 ovig. female [3.8].—Sta 5A–76, Shelly Beach: 6 males [3.8–5.0], 6 females [3.0–5.8], 3 ovig. [3.0–5.8].—Sta 8–76, McArthur Point 1 male [4.4], 3 ovig. females [2.8–5.0].

Other Collections: Olson (1970), McArthur Point, sandy bottom tide pool: 2 ovig. females [3.8–6.2].

SIZE.—Carapace lengths of males, 2.6–5.2 mm; of females, 1.7–6.2 mm; of ovigerous females,2.8–6.2 mm.

HABITAT.—All specimens listed probably were found in tide pools.

DISTRIBUTION.—Pantropical; eastern Atlantic from Senegal to Angola; central Atlantic from Ascension; western Atlantic from Bermuda and northeastern Gulf of Mexico to Tobago; eastern Pacific from Clipperton Island (Chace, 1962); widely distributed in central Pacific and Indian Oceans; to a depth of 20 meters.

Shallow-waters (0-100 m)