Prosphaerosyllis sotoi, Salcedo, Diana L., Martín, Guillermo San & Solís-Weiss, Vivianne, 2016

Salcedo, Diana L., Martín, Guillermo San & Solís-Weiss, Vivianne, 2016, Eusyllinae, Exogoninae and Autolytinae (Syllidae: Polychaeta) from the Southern Mexican Pacific, with the description of three new species, Zootaxa 4158 (4), pp. 507-522 : 517-520

Prosphaerosyllis sotoi n. sp.

( Figs 6–8 )

Sphaerosyllis (Prosphaerosyllis) sp. A: San Martín, 1991: 233 –235, Fig. 1 . Prosphaerosyllis sp. A: Capa, 2003: 181 –183, Fig. 77.

Material examined: 16 specimens: Holotype: complete specimen (CNAP–ICML POH–37–008), Palmitas E2B2 16°42.420’N, 99°54.733’W, 25 May 2006, 10.5 m, coarse sand. Paratypes: 5 specimens (CNAP–ICML POP–37– 009), El Jardín E3B1 16°49.436’N, 99°54.981’W, 26 May 2006, 12 m, coarse sand. 5 specimens (MNCN 16.01/ 16909), El Jardín E3B1 16°49.436’N, 99°54.981’W, 26 May 2006, 12 m, coarse sand. 5 specimens (NHMLA LACM-AHF Poly 7587), El Jardín E3B1 16°49.436’N, 99°54.981’W, 26 May 2006, 12 m, coarse sand.

Additional material: 125 specimens (CNAP–ICML PO–37–100): 3 specimens, Caleta E1B2 16°49.797’N, 99°54.062’W, 25 May 2006, 12 m, coarse sand. 27 specimens, Palmitas E2B1 16°42.420’N, 99°54.733’W, 25 May 2006, 10.5 m, coarse sand. 48 specimens, Palmitas E2B2 16°42.420’N, 99°54.733’W, 25 May 2006, 10.5 m, coarse sand. 30 specimens, El Jardín E3B1 16°49.436’N, 99°54.981’W, 26 May 2006, 12 m, coarse sand. 17 specimens, El Jardín E3B2 16°49.436’N, 99°54.981’W, 26 May 2006, 12 m, coarse sand.

Comparative material examined. Prosphaerosyllis sp. A: 2 complete specimens and a permanent slide (CM2F97), dead coral from Coiba National Park (Pacific coast of Panama).

Description. Holotype complete, 2.3 mm long, 0.3 mm wide, 29 chaetigers. Body short, preserved specimens without any color pattern. Prostomium oval, wider than long; two pairs of eyes in trapezoidal arrangement, located in the anterior part of the prostomium ( Fig. 6 A) and 2 eyespots near the anterior edge. Antennae all similar, small, piriform, with spherical bases and short tips; median antenna inserted between posterior eyes, lateral antennae inserted in front of anterior eyes ( Fig. 6 A). Palps short and wide, totally fused, covered with distinct papillae ( Figs 6 A, 8A). Peristomium short, well defined, similar in width to the other segments, with a pair of tentacular cirri similar to antennae but smaller, with abundant glandular material ( Fig. 6 A). Dorsum covered by small papillae, conical to round, in indistinct arrangement, more numerous on posterior half of body, where they become longer ( Fig. 6 A). Dorsal cirri absent in second parapodia; in the remaining chaetigers they are similar to antennae but slightly longer, piriform, not exceeding the length of parapodial lobes, with abundant glandular material which gives them a dark color ( Fig. 6 A). Ventral cirri short, digitiform, not exceeding the length of parapodial lobes. Parapodial lobes short, triangular, distally bilobed. Four to six heterogomph compound chaetae per chaetiger, with short, hooked, unidentate blades, with short spines on margin of anterior parapodia ( Figs 6 B, 8C), smooth or with barely distinguishable spines on remaining ones ( Figs 6 C, 7A, 8D). Chaetae similar all along the body, the length of the blades diminishing and the width increasing on the posterior region. Dorsal simple chaetae from first chaetigers unidentate, with acuminate tip and smooth on margins ( Figs 7 B, 8F). Ventral simple chaetae on posterior parapodia, unidentate, slightly curved and with short and fine spines on subdistal end ( Figs 7 C, 8E). One acicula per parapodium, slender, acuminate ( Fig. 6 D). Pharynx extending through five segments ( Fig. 8 A, 8B), with a conical tooth located on the anterior third of the pharynx, located well posteriorly from anterior margin ( Fig. 6 A). Proventricle similar in length, extending through about 4–5 segments, with about 18–19 muscle cell rows ( Fig. 6 A). Pygidium rounded, with a pair of anal cirri, similar in shape to dorsal cirri, but twice their length and with a thinner base.

Remarks. Prosphaerosyllis sotoi n. sp. is characterized by the absence of dorsal cirri on the second chaetiger and by having similar compound chaetae with short and hooked unidentate blades. The species Prosphaerosyllis magnoculata ( Hartman-Schröder 1986) and Prosphaerosyllis isabellae ( Nogueira, San Martín & Amaral 2001) have chaetae similar to the newly described species, but the former has larger eyes and straight and protruding aciculae, while both species have the median antenna located near the posterior margin of the prostomium, bulbous dorsal cirri and dorsal cirri on the second chaetiger. San Martín et al. (1991) and Capa (2003) previously described some specimens from Cuba and Panama respectively, as Prosphaerosyllis sp. A. These authors did not formally named their specimens as new species, given the small number of specimens they had, most of them incomplete.

Furthermore, Capa (2003) considered that the differences she observed between her specimens (from Panama) and those from Cuba were insufficient to consider them as two different species. For the present study, that material was carefully revised as well as the corresponding descriptions; since both agreed well with the diagnosis of the species herein described, they belong to P. s ot o i. n. sp. . There are some variations in the shape of the aciculae, since they are almost straight in the specimens from Cuba ; however, this feature was also observed in some specimens from Panama and from Acapulco Bay . The position of the pharyngeal tooth also varies, because in the specimens from Cuba it is located slightly closer to the anterior margin of the pharynx; however, this could be related to the size of the specimens, as happens with the length of the proventricle and the number of muscle cell rows.

Type locality. Acapulco Bay , Southern Mexican Pacific.

Habitat. Subtidal on medium to coarse sand.

Distribution. Cuba, Pacific coasts of Panama and Southern Mexican Pacific (Acapulco Bay).

Etymology. This species is named in honor to Dr Luis A. Soto, an enthusiastic and unflagging Mexican scientist devoted to the study of Benthic Ecology.

Figures

FIGURE 1. Odontosyllis septemdentata n. sp. (A) Anterior end, dorsal view. (B) Trepan (lp = lateral plates; t = teeth) Scale: 40 µm.

FIGURE 6. Prosphaerosyllis sotoi n. sp. (A) Anterior end, dorsal view. (B) Anterior chaetae. (C) Midbody chaetae. (D) Midbody acicula. Scale = 40 µm.

FIGURE 7. Prosphaerosyllis sotoi n. sp. (A) Posterior chaetae. (B) Dorsal simple chaeta (C) Ventral simple chaeta. Scale = 40 µm.

FIGURE 8. SEM micrographs of Prosphaerosyllis sotoi n. sp. (A) Anterior end, dorsal view. (B) Everted pharynx. (C) Anterior chaetae. (D) Posterior chaetae. (E) Ventral simple chaeta. (F) Dorsal simple chaeta. Scale: A = 50 µm; B = 10 µm; C, D, E, F = 5 µm.