Apionsoma (Edmondsius) pectinatum ( Keferstein, 1867 )

Silva-Morales, Itzahí & Gómez-Vásquez, Julio D., 2021, First records and two new species of sipunculans (Sipuncula) from the Southern Mexican Pacific, European Journal of Taxonomy 740 (1), pp. 77-117 : 95-97

Apionsoma (Edmondsius) pectinatum ( Keferstein, 1867)

Fig. 10

Phascolosoma pectinatum Keferstein, 1867: 47–48 (type locality: Pacific of Panama).

Siphonides rickettsi Fisher, 1952: 386–388 , pl. 22 (type locality: near La Paz, Baja California, Mexico, under boulders).

Phascolosoma (Satonus) pectinatum – E. Cutler 1977: 150 (from Gulf of Panama, Panama).

Material examined

MEXICO • 21; Oaxaca, Zipolite ; 15°39′37″ N, 96°30′38″ W; 16 Nov. 2016; FRE leg.; depth 2 m, in dead coral; UMAR-SIPU 011 • 8; Huatulco, San Agustín Bay ; 15°41′21″ N, 96°14′11″ W; 17 Nov. 2016; JGV leg.; depth 2 m, in dead coral; UMAR-SIPU 012 .

Description

Trunk 20 mm in length ( Fig. 10A ). Trunk light yellowish to dark brown in color, with dome-shaped papillae around trunk and base of introvert, scattered on body. Body wall wrinkled, giving a rough appearance ( Fig. 10B ). Introvert 2–4 times as long as trunk. Tentacles digitiform, encircling nuchal organ. Thirty rings of hooks in anterior region of introvert, with seven basal spinelets ( Fig. 10C ). Two pairs of retractor muscles. A pair of bilobed nephridia. Longitudinal bands of body wall show slight anastomosis. Nephridia with 40% of trunk length. Spindle muscle not attached to posterior end of trunk ( Fig. 10A ).

Remarks

With only a few records at the time, Cutler (1994) concluded that the distribution of Apionsoma (Edmondsius) pectinatum in the Eastern Pacific went from Baja California to Panama, so its distribution in the rest of TEP could only be inferred. This new record from the Southern Mexican Pacific breaks the disjunctive distribution in the Tropical Eastern Pacific for this species.

Habitat

Subtidal (2 m); in dead coral.

Distribution

Tropical Eastern Pacific, from Baja California Sur, Mexico to Gulf of Panama.

Figures

Fig. 10. Apionsoma (Edmondsius) pectinatum (Keferstein, 1867) from the Southern Mexican Pacific. A. Internal morphology. B. External morphology. C. Hook. Abbreviations: I = intestine; LMB = longitudinal muscle bands; N = nephridium; RM = retractor muscles.