Nymphon lituus Child, 1979

de Leon-Espinosa, Angel & de Leon-Gonzalez, Jesus A., 2015, Pycnogonids associated with the giant lion's-paw scallop Nodipectensubnodosus (Sowerby) in Ojo de Liebre Bay, Guerrero Negro, Baja California Sur, Mexico, ZooKeys 530, pp. 129-149 : 135-138

Taxon classification Animalia Pantopoda Nymphonidae

Nymphon lituus Child, 1979 Fig. 4

Nymphon lituus Child 1979: 38-40, fig. 13.

Material examined.

Ojo de Liebre Bay, Guerrero Negro, Baja California Sur, scallop fishing areas: Chocolatero, 27°53'04"N, 114°15'06"W, (UANL-FCB-PYCNO-0048), AH-28, (1♂), 01/10/2012; El Datil, 27°48'43"N, 114°15'06"W, (UANL-FCB-PYCNO-0049), AD-8, (1♂, 1♀), 01/12/2012; La Concha, 27°50'35"N, 114°16'22"W, (UANL-FCB-PYCNO-0050), AC-11, (1♂), 01/12/2012; (UANL-FCB-PYCNO-0051), AC-14, (1♂); (UANL-FCB-PYCNO-0052), AC-15, (1♀), 01/10/2013; (UANL-FCB-PYCNO-0053), AC-10, (1♂), 22/11/2013.

Description.

Proboscis cylindrical, longer than wide, horizontal to body (Fig. 4A), with three smooth lips.

Chelifore with two segments, the scape cylindrical. Fingers of the chela slender, longer than the basal part, which is inflated and rectangular, with a single median dorsal spine and 3 large dorsal setae in a row at the distal end, next to the articulation with the movable finger; and 2 long and 3 shorter setae on the ventral surface. The fixed finger has 29-30 slender chela teeth. Upper movable finger without setae, armed with 25 small teeth. The tips of the fingers slightly curved, overlapping distally (Fig. 4B).

Palps of five segments. First segment, very short. Second segment longest, with one large dorsodistal seta. Third segment is 2/3 the length of segment two with three ventral isolated setae. Fourth segment twice as long as segment one, with a ventral row of eight setae. Fifth segment 1.5 times as long as fourth segment, with two parallel rows of nine and seven long ventral setae, terminal end with a cluster of four setae (Fig. 4C).

Ocular tubercle inserted between the first pair of lateral processes, cone-shaped, with two small projections in the form of papillae, with two pairs of eyes (Fig. 4A).

Trunk slender, segmented. Neck 4.5 times longer than its width, smaller, cylindrical, widening in the form of a calyx, with a pair of conical, short anterior projections (Fig. 4A).

Lateral processes between first and second pairs separated slightly by their own diameters, second and third pairs separated by 1.5 times their diameters, and third and fourth pairs separated by less than their own diameters (Fig. 4A).

Legs long and slender (Fig. 4F, G). Coxa I short, without setae. Coxa II two times longer than coxa I, with two ventral anterior setae. Coxa III slightly longer than coxa I, with a row of four small ventral setae. Femur long, with one dorsal seta and scattered ventral setae. Tibia I with a single long median dorsal seta, and a ventral row of 9 smaller setae. Tibia II with a row of 45-50 small ventral setae, and 8-9 dorsal setae. Tarsus half as long as propodus with 10-11 ventral setae, a lateral row of six setae and a dorsal row of four setae. Propodus two times longer than tarsus, slightly curved, with a row of 19-20 sole spines, a median lateral row of ten spines, and two dorsal rows of 18-20 spines each, one row composed of short and the other of long spines. Main claw short, less than ¼ the length of the propodus, auxiliary claws nearly as long as main claw (Fig. 4G).

Oviger (Fig. 4D, E) inserted in the distal half of the first lateral process. First three segments short, first segment is half the size of the second one, second and third segments are subequal. Fourth and fifth segments longest, subequal. Fourth segment with two short ventral setae, and one long ventrodistal spine, fifth segment with a ventral row of three setae and one long ventrodistal spine. Sixth segment as long as the first and second together, with a ventral row of three setae. Last four segments armed with compound ovigerous leg spines, each with the following formula: 13: 9: 8: 10. Compound spines with 3-6 pairs of lateral teeth depending upon the size of the spine. Terminal claw long, curved, with six teeth (Fig. 4E).

Female gonopores oval in shape, present on ventrodistal end of coxa II of all leg pairs. These were observed on only two specimens (AD-8 and AC-15). All other specimens (males) without readily visible gonopores.

Abdomen as long as lateral processes of 4th pair of legs, elevated from the body at an angle of about 30° (Fig. 4A).

Standard measurements.

Proboscis 0.57 mm long, 0.28 mm wide.

Body 1.43 mm long from anterior end of cephalic segment to end of 4th lateral processes, 1.0 mm wide between second pair of lateral processes.

Leg 1 9.35 mm long from coxa I to the tip of main claw. Coxa I, 0.37 mm, coxa II, 0.71 mm, coxa III, 0.41 mm, femur 1.84 mm, tibia I, 2.02 mm, tibia II, 2.78 mm, tarsus, 0.35 mm, propodus 0.71 mm, claw 0.16 mm.

Oviger 3.19 mm long, first segment 0.78 mm, second 0.81 mm, third 0.38 mm, fourth 0.44 mm, fifth 0.19 mm, sixth 0.22 mm, seventh 0.38 mm, eighth 0.24 mm, ninth 0.24 mm, tenth 0.21 mm.

Distribution.

This species is known from Gulf of California and Panama: specimens from Gulf of California were taken on floating Sargassum around Puerto Peñasco, Sonora, and in Panama City, among hydroids and bryozoans ( Child 1979, p. 40). With this record, the distribution of Nymphon lituus is extended to the western coast of Baja California Peninsula.

Remarks.

The genus Nymphon includes 277 valid species ( Bamber et al. 2015). Despite the great diversity of the genus, only ten species are known from the eastern Pacific: Nymphon aculeatum Child, 1994 from San Clemente Basin, California; Nymphon apheles Child, 1979 from Panama; Nymphon duospinum (Hilton, 1942) from Alaska; Nymphon heterodenticulatum Hedgpeth, 1941 from Santa Catalina Island, southern California; Nymphon hirsutum Child, 1995 from the Bering Sea; Nymphon lituus Child, 1979 from the Gulf of California and Panama; Nymphon longicollum Hoek, 1881 from Chile (also from New Zealand and Auckland Islands); Nymphon pixellae Scott, 1912 from Vancouver, Canada (also from California and Japan); Nymphon similis Child, 1992 from Ecuador; and Nymphon stipulum Child, 1990 from southern California. Nymphon lituus is a species known only from its original description; the specimens found in this study vary slightly in the number of compound ovigerous leg spines, with the formula 13: 9: 8: 10, in contrast to the original description of Nymphon lituus with the formula 15: 10: 10: 11. The other features do not present major variations.