First records and two new species of sipunculans (Sipuncula) from the Southern Mexican Pacific Author Silva-Morales, Itzahí ADA5A4BD-EB4E-47E3-A6A7-D3E1FDA64ED3 División de Posgrado, El Colegio de la Frontera Sur, Unidad Chetumal, Quintana Roo, Mexico. itzahi_marley.gwn@hotmail.com Author Gómez-Vásquez, Julio D. BD3A3DE1-21F5-4B54-A707-361BE8E90DB9 Laboratorio de Sistemática de Invertebrados Marinos (LABSIM), Universidad del Mar campus Puerto Ángel, Ciudad Universitaria, Puerto Ángel, Pochutla, Oaxaca 70902, Mexico. gomezvjuliod@gmail.com text European Journal of Taxonomy 2021 2021-03-25 740 1 77 117 http://dx.doi.org/10.5852/ejt.2021.740.1283 journal article 7588 10.5852/ejt.2021.740.1283 504278d0-5689-4adb-9350-3e97392bfbf0 2118-9773 4643194 07F1B593-9F4F-4B32-88D9-ADC5CA0BEB84 Aspidosiphon ( Paraspidosiphon ) cutleri sp. nov. urn:lsid:zoobank.org:act: 48C0AFB4-02DD-4164-9223-BDA2CC1D0A43 Fig. 12 Etymology In memory of Edward Cutler, expert in sipunculans and the principal source of inspiration for this work. Material examined Holotype MEXICO • Oaxaca , Camarón Beach ; 15°39′45″ N , 96°31′33″ W ; 6 Apr. 2013 ; in dead coral; RXP and VAR leg.; UMAR-SIPU 082. Paratypes MEXICO • 1; same locality as for holotype ; 16 Nov. 2016 ; JGV leg.; depth 2 m , in rocks, UMAR-SIPU 083 • 1; Oaxaca , San Agustin Bay ; 15°41′21.1″ N , 96°14′11.1″ W ; 18 Mar. 2018 ; depth 2 m , in rocks; UMAR-SIPU 107 . Description Trunk 30 mm in length, white ( Fig. 12A ). Anal and caudal shield brown. Sixteen longitudinal grooves in anal shield. Caudal shield also with grooves ( Fig. 12C–D ). Units of anal region distributed in longitudinal lines ( Fig. 12E ). More than 100 rings of unidentate proximal hooks, smaller than distal hooks ( Fig. 12F ) followed by scattered pyramidal hooks. Longitudinal muscles of body wall gathered into anastomosing bands. A pair of retractor muscles, fused for most of their length. Nephridia unilobed, occupying 50% of the trunk. Spindle muscle bifurcated near its anterior end ( Fig. 12B ). Fig. 12. Aspidosiphon ( Aspidosiphon ) cutleri sp. nov. , holotype (UMAR-SIPU 082), from the Southern Mexican Pacific. A . External morphology. B . Internal morphology. C . Anal shield, dorsolateral view. D . Anal shield, dorsal view. E . Anal shield, lateral view. F . Distal unidentate hooks. Abbreviations: I = intestine; LM = longitudinal muscle; N = nephridium; RM = retractor muscles. Remarks The species that are most similar to Aspidosiphon ( Paraspidosiphon ) cutleri sp. nov. are A . ( P .) coyi de Quatrefages, 1865 , described from the Indian Ocean, and A . ( P .) laevis de Quatrefages, 1865 . The type material of these two species was described by Saiz-Salinas (1983) . The main differences between these species are the following: Aspidosiphon ( P. ) coyi has bidentate hooks and disperse units in the anterior region of the trunk; Aspidosiphon laevis lacks bidentate hooks and the units on the anterior region of the trunk are dispersed; nephridiopores are at the same level as the anus in both these species; on the other hand, A. (P.) cutleri sp. nov. only has unidentate hooks and the units are distributed in lines on the anterior region of the trunk; the nephridiopores are posterior to the anus. It is likely that the record of A . ( P .) laevis from Costa Rica ( Dean et al . 2010 ) corresponds to this new species; however, it is necessary to review the specimens. Habitat Subtidal ( 2 m ); in dead coral. Distribution Oaxaca , Mexico .