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

unequal lobules occupying almost 90% of trunk length (Fig. 9B). Spindle muscle attached to body wall posteriorly.

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.