First records and two new species of sipunculans (Sipuncula) from the Southern Mexican Pacific Author Silva-Morales, Itzahí ADA5A4BD-EB4E-47E3-A6A7-D3E1FDA64ED3 0000-0002-0796-0667 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 10.5852/ejt.2021.740.1283 504278d0-5689-4adb-9350-3e97392bfbf0 2118-9773 4643194 07F1B593-9F4F-4B32-88D9-ADC5CA0BEB84 Apionsoma ( Apionsoma ) hespera ( Chamberlin, 1920 ) comb. nov. , reinstatement Figs 8A–C , 9 Phascolosoma hespera Chamberlin, 1920: 31 ( type locality: Balboa, Newport Bay, Orange County, California ). Golfingia hespera – Fisher 1952: 393–395 , pl. 24, figs 1–5 (San Lucas Cove, southern Santa Rosalía, Gulf of California , commensals in Cerianthus Delle Chiaje, 1841 tubes; Balboa, Newport Bay, Orange County, California ). Golfingia ( Mitosiphon ) hespera – Amor 1975: 115–116 , pl. 2, figs a–d (Ancón, Peru in Phragmatopoma Mörch, 1863 and Perumytilus Olsson, 1961 , in rocks). Material examined MEXICO – Oaxaca • 1; Chacahua ; 15°58′07″ N , 97°32′09″ W ; 4 Apr. 4, 2007 ; artificial monticule, in rocks; UMAR-SIPU 101 • 3; Panteón Beach ; 15°39′50″ N , 96°29′42″ W ; 24 Apr. 2012 ; NVHH leg.; UMAR-SIPU 102 . Description Trunk 8 mm in length, spindle-shaped ( Fig. 9A ). Introvert seven times trunk length. Posterior end of trunk with numerous distinctive papillae ( Fig. 9C–D ). More than 40 rings of hooks, with 7–8 basal spinelets. Spinelets longer than principal tooth ( Fig. 9E ). Body wall with continuous muscle layers. Four retractor muscles equidistant from ventral nerve cord near middle of trunk. Nephridia bilobed, with Fig. 8. – A–C . Hooks of Apionsoma ( Apionsoma ) hespera ( Chamberlin, 1920 ) comb. nov. A . From Oaxaca, Mexico. B–C . From Peru. – D–E . Hooks of Apionsoma misakianum ( Ikeda, 1904 ) . D . From Misaki, Japan. E . From Japan. B–C: from Amor (1975) ; D: from Ikeda (1904) ; E: from Cutler et al . (1984) . unequal lobules occupying almost 90% of trunk length ( Fig. 9B ). Spindle muscle attached to body wall posteriorly. Fig. 9. Apionsoma ( Apionsoma ) hespera ( Chamberlin, 1920 ) comb. nov. from the Southern Mexican Pacific. A . External morphology. B . Internal morphology. C . Caudal papillae. D . Caudal papillae, amplified view. E . Hooks. Abbreviations: DRM = dorsal retractor muscles; I = intestine; LM = longitudinal muscle; N = nephridium; VRM = ventral retractor muscles. Table 4. Comparison between the species of Apionsoma Sluiter, 1902 .

Phascolosoma hespera	Apionsoma ( A. ) misakianum	Apionsoma ( A. ) hespera comb. nov.
Reference	Chamberlin (1920)	Ikeda (1904)	this paper
Locality	Laguna Beach, California, USA	Misaki, Japan	Panteón Beach, Oaxaca, Mexico
Number of rings of hooks	30–50	60	40
Basal spinelets	7	4–5	7–8
Proportion between distance of dorsal to ventral muscle with respect to the trunk	10%	21%	10%
Nephridia extent	100% of trunk	<50% of trunk	80% of trunk
Longitude of basal spinelets	longer than principal tooth	shorter than principal tooth	longer than principal tooth

Remarks We reinstate the name Phascolosoma hespera in the correct genus as the new combination Apionsoma ( Apionsoma ) hespera . The most similar species to A. ( A .) hespera comb. nov. is A . ( A .) misakianum ( Ikeda, 1904 ) from Misaki, Japan ( Table 4 ). Fisher (1952) illustrated type material and he showed the morphological and ecological differences between the two species. Cutler (1979) considered Phascolosoma hespera Chamberlin, 1920 and Golfingia hespera sensu Fisher 1952 as synonyms of A. ( A .) misakianum , but we believe that the morphological features are enough to consider P. hespera as a valid name with a distribution in the TEP. We compared the illustrations of the hooks of A. ( A. ) misakinaum , from Misaki ( Ikeda 1904 ; Fig. 8D ) and other localities of Japan ( Cutler et al . 1984: 300–301 ; Fig. 8E ), with the hooks of the specimens revised in this study ( Fig. 8A ) and those of specimens recorded from Peru as Golfingia ( Mitosiphon ) hespera ( Amor 1975 ; Fig. 8B–C ). Staton & Rice (1999) stated that there is strong reproductive isolation between the northern and southern populations of the A. misakianum species complex, another argument to consider that A. hespera is a valid species and likely could be part of this species complex. Habitat Intertidal, in Cerianthus tubes, in rocks with Phragmatopoma and Perumytilus . Distribution Laguna Beach, California; Tropical Eastern Pacific from Baja California Sur to Oaxaca; Ancón, Peru .