Pseudopotamilla sp.

Tovar-Hernández, María Ana, León-González, Jesús Angel De & Hendrickx, Michel E., 2025, Polychaeta collected during the research cruises TALUD aboard the R / V “ El Puma ” in the Mexican Pacific: Sabellidae and Serpulidae, Zootaxa 5663 (1), pp. 1-80 : 65-67

Pseudopotamilla sp.

( Fig. 36 )

Material examined. ICML-EMU-14050: TALUD XIV, St. 33, BS, 27º47'52"N 111º09'30"W, 11 April 2011, 319– 344 m, 2 specimens .

Description of material examined. Specimens incomplete, lacking posterior end, + 23 mm long, thorax 1.6 mm wide. Branchial crown 9–10 mm long with 12 pairs of radioles. Thorax with eight chaetigers. Abdomen with + 22 chaetigers. Branchial crown asymmetrical with longest radioles dorsally, then decreasing towards ventralmost radioles, which are 1/4 de length of the dorsalmost radiolar pair. Radiolar lobes short, with dorsal and ventral flanges. Radiolar flanges and palmate membrane absent. Pinnules arranged in two alternating rows, longest at the mid-radiolar length. Radiolar tips short, as long as space of three pinnules width. Compound radiolar eyes proximal (basal half of branchial crown) on radiole 4, rounded ( Fig. 36D ). Radioles 3 and 5 with dark spots near the same distance than compound eye of radiole 4 ( Fig. 36D ). Radiolar eyes formulae: xxx1xxxxxxxx. Relation between radioles with eyes and total number of radioles: 1/12. Anterior peristomial ring partially exposed dorso-lateralventrally between dorsal pockets and lateral collar margin ( Fig. 36A–C ). Posterior peristomial ring collar with dorsal margins fused to faecal groove ( Fig. 36A ); mid-dorsal margins low, not longer than the base of radioles ( Fig. 36A ). Ventral lappets sub-rounded, divided mid-ventrally by short incision ( Fig. 36B ). Peristomial eyes not seen. Lateral sides of anterior peristomial ring with oval brown spots ( Fig. 36C ). Dorsal lips triangular, erect, with mid-rib (radiolar appendages); ventral lips short, rounded. Ventral sacs present. Chaetiger 1: two rows of broadly-hooded notochaetae. Ventral shield of collar rectangular, slightly divided transversally, higher than the following thoracic shields. Chaetigers 2–8: ventral shields rectangular, divided transversally in two equal parts; tori not contacting ventral shields (separated by a reduced space) ( Fig. 36B ); superior notochaetae elongate narrowly hooded ( Fig. 36E–F ); inferior ones paleate, arranged in two rows, with pointed mucro ( Fig. 36E ). Neuropodial avicular uncini with several rows of small, similar sized teeth above main fang, breast well developed ( Fig. 36G, I ); handles as long as two times the length of main fang, a high crest and short neck (as long as 1/2 the length of main fang) ( Fig. 36I ). Companion chaetae with symmetrical membranes, teardrop-shaped ( Fig. 36G–H ), and long handles, as long as handles of uncini. Abdominal neurochaetae elongate broadly-hooded ( Fig. 36J ). Notopodial uncini with several rows of teeth above main fang with a high crest, breast well developed, handles short, as long as the length of main fang ( Fig. 36K–M ). Pygidium unknown.

Remarks. The specimens from the TALUD project cannot be properly compared with the four Californian species of the genus: P. debilis Bush, 1905 , P. intermedia Moore, 1905 , P. occelata Moore, 1905 and P. socialis . In the four species original illustrations includes chaetae and uncini only, not showing taxonomically useful variations among these taxa. Pseudopotamilla debilis was described with “a few scattered eyes” (Bush 1905: 204); P. intermedia described with “never more than 2 eyes, and sometimes one or none, occur on each stem” ( Moore, 1905: 563); P. occelata with “The ventral stems commonly bear 5 or 6 eyes, occasionally as few as 3, usually distant or in couples. On the dorsal half of the circle of branchiae each shaft bears from 7to 12…”, and P. socialis described as “Eyespots variable, sometimes totally lacking, or occur singly, or may number 3 or 5 on a radiole”, a variation also reported in the present study. Specimens from the TALUD project have only one eye on the radiole 5, and this does not match with any of the above mentioned species. In addition, Pseudopotamilla intermedia was also reported by Rioja (1941) from shallow waters in Acapulco, Guerrero, Mexico, but diagnosis or drawings were not included and it is therefore impossible to compare his material with the specimens collected during this survey. However, as demonstrated in the case of P. socialis in the present study, the infraspecific variation of presence and number of eyes is high. Only two specimens were collected and there is a need to obtain additional specimens to complete the study. The three Californian species cited above should also be redescribed.

Abiotic conditions. The specimens of Pseudopotamilla sp. were collected from 319‒344 m deep; temperature: 10.4°C. No more data available on environmental conditions ( Table 1).

Distribution. Northern Gulf of California, Mexico.

SERPULIDAE Rafinesque, 1815

Genus Hyalopomatus Marenzeller, 1878

Figures

FIGURE 36. Pseudopotamilla sp. A) Thorax, dorsal view, B) same, ventral view, C) same, lateral view, D) right branchial lobe showing compound eye in radiole 4 and reminiscent spots on radioles 3 and 5, E) thoracic chaetiger, F) superior group of thoracic narrowly hooded chaetae, G) thoracic torus showing uncini and companion chaetae, H) companion chaeta, I) thoracic uncinus, J) abdominal chaetae broadly hooded, K–M) abdominal uncini. Abbreviations: 3, 4, 5—refers to the number of radioles. Scale bars: A–D) 1 mm, E) 50 μm, F, H–I) 22 μm, G) 100 μm, J) 30 μm, K–M) 10 μm. A–M: ICML-EMU-14050.