Synalpheus brevispinis Coutière, 1909

Salazar, Margarita Hermoso, Wicksten, Mary & Morrone, Juan J., 2005, Redescriptions and taxonomic notes on species of the Synalpheus townsendi Coutière, 1909 complex (Decapoda: Caridea: Alpheidae), Zootaxa 1027 (1), pp. 1-26 : 21-24

Synalpheus brevispinis Coutière, 1909

Figs. 9–10

Synalpheus townsendi brevispinis Coutière, 1909: 33 , fig. 16.— Ray 1974: 177.

Material examined: GULF OF CALIFORNIA, MEXICO: Puerto Peñasco, Sonora, 13 April 1988, A. Kerstitch: 1 specimen. Calerita, Baja California Sur, in coral heads; intertidal; 23 July 1997, L. Hernández: 6 specimens (3 of them ovigerous). Los Islotes , Baja California Sur, from coral (no other data): 1 specimen. Punta Chileno , Cabo San Lucas : 5– 10 m, 22­25 July 1981, A. Kerstitch, 1 specimen ( LACM) . GALAPAGOS ISLANDS: Wolf Island , 7 February 2000, scuba, subtidal, C. Hickman Jr.: 1 specimen .

Description

Rostrum subtriangular, apex straight in lateral view, 2.4 times longer than wide, reaching 0.8 times length of visible part of first segment of antennular peduncle, exceeding orbital teeth in lateral view, originating over the surface of the carapace. Orbital hoods slightly inflated; orbital teeth subtriangular, distal portion sharp, apex slightly directed mesially in dorsal view and straight in lateral view, lateral margins slightly convex, shorter than rostrum, without setae, reaching 0.4 times length of visible part of first segment of antennular peduncle. Anterior margin of carapace between rostrum and orbital teeth slightly concave, with slight depression visible on the surface of carapace between rostrum and orbital hoods. Ventral rostral process curved and laterally narrow, markedly bilobed. Pterygostomial angle of carapace sharply produced, antennal margin sinuous.

Antennular peduncle somewhat thick, total length 3.9 times width. First segment of antennular peduncle slightly longer than second and third segments combined, 1.1 times length of second segment, length of second segment subequal to that of third segment. Stylocerite wide proximally and distally sharp, reaching 0.7 times length of second segment of antennular peduncle.

Blade of scaphocerite well developed, length 2.5 times width, almost reaching distal end of antennular peduncle. Tooth of scaphocerite almost straight, lateral margin slightly concave, exceeding scale by 0.4 times length of third segment of antennular peduncle, often reaching to distal end of third segment of antennular peduncle, shorter than carpocerite by approximately 0.4 times length of third segment of antennular peduncle. Dorsal tooth of basicerite absent; lateral tooth thin, almost reaching distal end of visible part of first segment of antennular peduncle, exceeding rostrum and orbital teeth. Carpocerite 3.6 times as long as wide, equal to or overreaching antennular peduncle by approximately half of length of third segment of antennular peduncle.

Length of ultimate segment of third maxilliped 4 times length of the penultimate segment, distal end with five dark spines.

Ischium of major first pereopod 0.6 times as long as wide. Length of merus 2.1 times width, 0.9 times length of palm, dorsal margin somewhat convex, ventral margin slightly concave, distal end of dorsal margin with tooth pointed downward. Carpus short, distal end of dorsal margin with tooth on external face, not elongated, ventral margin somewhat bilobed. Chela somewhat inflated, length of chela 2.8 times its width, length of palm 1.9 times its width, 2.3 times length of fingers, distal end of dorsal margin of palm with a lobule, fingers short, 0.3 times length of chela.

Ischium of minor first pereopod 1.2 times as long as wide, 0.3 times length of merus. Length of merus 2.3 times width, dorsal and ventral margins slightly convex, distal end of dorsal margin with spine pointed downward. Length of carpus 0.9 times width, 0.4 times length of palm, distal tip of dorsal margin with spine on external face, not elongated. Length of palm of chela 1.7 times width, 1.2 times length of fingers, with sparse setae on chela and fingers.

Second pereopod slender and chelate. Length of ischium of second pereopod 0.8 times length of merus. Length of merus 5.5 times its width, 0.8 times length of carpus. Carpus slender, with five segments having ratios of length from first to fifth as follows: 5:1:1:1:3. Length of palm 1.5 times its width, 0.8 times length of fingers, two patches of setae on fixed finger, some setae on movable finger

Ischium of third pereopods 2.2 times as long as wide. Length of merus 4.7 times its width. Length of carpus 3.5 times its width, 0.5 times length of propodus. Length of propodus 8.4 times its width, 3.6 times length of dactylus, ventral margin with 6 movable spines and 1 pair distal spines. Dactylus long and thin, length 4.4 times maximum width, inferior tooth diverging slightly from central axis of dactylus, width of base of teeth subequal. Fourth and fifth pereopods similar but shorter, fifth pereopod with patches of short setae on flexor margin of propodus.

Posterior end of ventral margin of pleura of first abdominal somite with marked sexual dimorphism: in male, slightly produced, rounded in female. Ventral margins of pleura of second abdominal somite subquadrate, fifth pleura somewhat angular. Second pleopod with appendix interna only in females. Telson wide, length 1.3 times its anterior width, 2.1 times its posterior width, dorsal surface without median longitudinal depression, lateral margins convex at half their length, posterior margin markedly convex. Dorsal spines short, removed from lateral margin, anterior pair of spines inserted at 0.5 times length of telson, posterior pair at 0.7 times length of telson. Distal angles of telson slightly produced. Spines of posterior margin thin, length of mesial pair 3.5 times length of lateral pair. Uropodal exopod with margin slightly sinuous, diaresis with two teeth: one strong lateral tooth, mesial tooth minute, with spine between them.

Carapace length to 5.0.

Color in life.— Not reported.

Type locality. — Lower California .

Habitat.— Among rocks and coral heads.

Geographic distribution and depth range.— Puerto Peñasco, Sonora (northern Gulf of California) to Wolf Island , Galapagos (this paper), intertidal to 10 m.

Remarks.— As in S. townsendi , the sexual dimorphism of the pleura of the first abdominal somite is marked. Another useful feature to distinguish between the sexes is the absence of an appendix interna on the second pleopod of the male.

The length of the rostrum and orbital teeth varies. The rostrum often exceeds the midlength of the first segment of the antennular peduncle. The orbital teeth do not exceeding half of the length of the first antennular segment. The range of variation in the ratio of length to width of the antennal blade is between 2.4 and 2.8. Often, it reaches the distal third of the third segment of the antennular peduncle. The ventro­lateral tooth of the basicerite may or may not reach the distal end of the first segment of the antennular peduncle. The dorso­lateral margin of the carpus of the major and minor chelipeds often has a small tooth on the external face.

Figures

FIGURE 9. Synalpheus brevispinus Coutière, 1909. A, frontal region. B, rostrum and ocular hoods. C, ventral rostral process. D, third maxilliped. E, major cheliped. F, minor cheliped.

FIGURE 10. Synalpheus brevispinus. A, second pereopod. B, third pereopod. C, female abdomen. D, second pleopod. E, telson and uropods.