Ammothella symbia Child, 1979

(Fig. 4 A–F; 5 A–K)

Ammothella symbius Child, 1979: 12–15, fig. 4; M̹ller, 1993: 32.

Ammothella symbia Child, 2004: 184 (in taxonomic key); Bamber & Takahashi, 2005: 2.

Material examined. 4 specimens: 1³, (UANL-FCB-PYCNO-0058), FONATUR marine, Santa Rosalía, Baja California Sur, Mexico, 27°20´13´´N, - 112°15´47´´W, 01/11/2013; 2³, (UANL-FCB-PYCNO-0059); same sampling location, 11/15/2013; 1³, (UANL-FCB-PYCNO-0060), Cabo San Lucas Marine, Cabo San Lucas, Baja California Sur, Mexico, 22°53´09´´N, - 109°54´38´´W, 7/01/2013 (Fig. 1) .

Description. The best-preserved specimen is a male with oval body, fully segmented, glabrous except for a small tubercle and one anterior and one posterior seta on each lateral process; which are separated by less than ½ of their own diameter (Fig. 4 A; Fig. 5 E). Cephalon with a low latero-distal tubercle. Ocular tubercle cylindrical, 3.3 times longer than wide, with two pairs of oval eyes, distal end as a small cone (Fig. 4 B; Fig. 5 A, D). Elongated abdomen, six times longer than wide, inserted at a 30° angle upward, with a group of four long setae on dorsal view, and two setae on the distal end (Fig. 4 A–B, Fig. 5 K). Proboscis oval, two times longer than wide, triangular mouth, triangular lips with a band of small setae (Fig. 4 A–B; Fig. 5 A, C).

Chelifore ¾ the length of the proboscis, scape with two articles, first one small, ½ the size of the second article, armed with a dorsal tubular seta; second article armed with two tubular setae in tandem, as well as several sharp setae, chela atrophied, conical (Fig. 4 A–B; Fig. 5 A–B).

Palp with nine articles. First, third and eighth articles short, first one glabrous, third with a ventral seta, eighth article with a dorsal and a ventral seta. Second article three times longer than the first one, with a median-ventral seta and two anterior dorsal setae. Fourth article is the longest, with two pairs of anterior-dorsal and ventral setae. Fifth article with three pairs of ventral setae. Sixth and seventh articles similar in size, the sixth with two pairs of ventral setae, one middle and one anterior respectively, as well as a middle-dorsal seta; the seventh with a pair of ventral setae inserted anteriorly, and an anterior-dorsal seta. Ninth article twice as long as the first, with two longitudinal rows of setae, the longest row with nine setae, and the shorter row with four (Fig. 4 C; Fig. 5 C).

Oviger with 10 articles. First five articles glabrous, unarmed, fourth longest. Sixth article with a ventral seta. Seventh article expanded laterally, armed with three long dorsal setae, a lateral seta and a row of three ventral denticulate spines with 3, 7, and 10 pairs of serrations respectively. Eighth article with a dorsal seta and two ventral denticulate spines armed with 8 and 12 pairs of serrations. Ninth article with a proximal dorsal seta and a ventral denticulate spine with 12 pairs of serrations. Tenth article small, with two distal denticulate spines, each with with 11–12 pairs of serrations. Terminal four oviger articles with denticulate spine formula 3: 2: 1: 2 (Fig. 4 F; Fig. 5 I–J).

Legs of similar shape (Fig. 5 F). Coxa 1 small, rounded, with an anterior tubular seta, two lateral setae and a ventral one. Coxa 2 with two latero-anterior sharp setae and a median tubular one, two ventro-distal setae. Coxa 3 with a long middle-dorsal seta, a group of four middle-ventral setae, a ventro-distal seta and two anterior-lateral setae. Femur longer than coxa 1 to 3 combined, with a long dorsal seta, a row of four lateral setae and a pair of ventral ones. Femoral cement gland tubular, as long as article diameter, arising dorso-distally from low tubercle (Fig. 4 D). Tibia 1 and 2 the same size as the femur, both with numerous setae. Tarsus small, with a dorsal seta longer than the ventral ones. Propodus with a row of five dorsal spines, two latero-dorsal setae, a row of three lateral setae, and a row of five anterior setae decreasing in size toward the ventral side. Heel with three thick basal spines followed by a row of six short sole spines. Main claw strong, curved; auxiliaries slightly curved, 2/3 length of main claw length (Fig. 4 D–E; Fig. 5 G–H).

Measurements of the illustrated specimen (mm). Trunk length from the chelifore insertion to tip of fourth lateral processes, 1.02; trunk wide across second lateral processes, 0.9; proboscis length 0.92, 0.44 wide.

Third leg: Coxa 1, 0.21; coxa 2, 0.38; coxa 3, 0.29; femur 0.72; tibia 1, 0.84; tibia 2, 0.97; tarsus, 0.13; propodus 0.46; main claw 0.21.

Oviger: 1) 0.1; 2) 0.18; 3) 0.18; 4) 0.36; 5) 0.23; 6) 0.13; 7) 0.14; 8) 0.1; 9) 0.13; 10) 0.3.

Distribution. Child (1979) reported Ammothella symbia in Mazatlán, Sinaloa, Mexico, as well as in Cocos Island, Costa Rica; and in channel zone of the Pacific coast of Panama, Punta Paitilla, Taboguilla Island, and Las Perlas Archipelago, Panama. The closed report from the record at Bahía de La Paz reported in the present study was about 470 km east at Mazatlán, Sinaloa, Mexico.

Remarks. Ammothella symbia is morphologically similar to A. spinifera . The specimens from the present study were 20–30% longer and wider than the holotype first described from Costa Rica (Child 1979). The number of spines on the legs of the holotype was lower than the numbers of spines on the specimens analyzed in the present study. A shared character was the presence of three thick spines on the heel and six smaller spines on the sole. Ammothella symbia also has shorter chelifores than A. spinifiera . One of the diagnostic characters of A. symbia is the lack of setae on the dorsal trunk surface.