Myxicola bruscai, Tovar-Hernández & León-González & Hendrickx, 2025

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 : 42-46

Myxicola bruscai sp. nov.

urn:lsid:zoobank.org:act:D8711DFC-C6C4-4B36-9CDC-96E04039A3EC

( Figs 22–24 , 40A–D , Table 3)

Material examined. Type material. Holotype, UANL-8273: Southern Gulf of California , Baja California Sur , San Gabriel , Isla Espíritu Santo , Bahía de La Paz, 24º25'37"N 110º22'12"W, 3 m, April 2014, Coll. de León-González, J.A.

Description. Body plump, cylindrical, purple in thorax ( Fig. 22A ). Trunk 30 mm long, thorax 4 mm wide. Branchial crown 20 mm long, with semi-circular radiolar lobes fused dorsally, bearing 20 pairs of radioles. Thorax with eight chaetigers. Abdomen incomplete, only 15 chaetigers (posterior end missing). Palmate membrane along 3/4 of the radiolar length ( Figs 23A , 24A ). Radiolar flanges extend above the distal margin of palmate membrane for a short distance ( Fig. 24C ). Radiolar tips bare, filiform without radiolar flanges, 4.5 mm long (as long as 1/4 the radiole length) ( Figs 23A , 24A–B ). Each radiole with a pair of oval compound eyes ( Figs 23A–E , 24B ), each eye with tear-drop shaped ommatidia ( Fig. 23B, D–E ). Dorsal lips short, rounded (ear-shaped seen from inner margins of radiolar lobes) without radiolar appendage ( Fig. 24C–D ) (not visible in any angle of view). Ventral lips extending dorsoventrally along inner surface of base of radiolar lobes and connecting ventrally to the radiolar lobes. Parallel lamellae and ventral sacs absent. Posterior peristomial ring collar absent. Anterior peristomial ring with triangular ventral lobe, distally entire ( Fig. 22C ); laterally with a deep groove extending to the collar chaetiger ( Fig. 22F ). Two whitish glandular ridges: a narrow one on chaetiger 1, a broad one on chaetiger 2 ( Fig. 22B–C, E–F ). Ventral shields absent throughout. Interramal eyespots absent. Thoracic chaetigers with almost inconspicuous notopodia, surrounded by a purple oval-shaped areas ( Fig. 22F ), with elongate, narrowly hooded chaetae ( Figs 23G , 39A ). Thoracic neuropodia with acicular uncini with curved tips as hooks, each equipped with two narrow teeth above the main fang, hood absent ( Figs 23H , 39B ). Companion chaetae absent. A pair of whitish, longitudinal glandular bands in thoracic segments 5–8 and in all abdominal segments, located dorsally and ventrally ( Fig. 22D pointed with arrows, G). Lateral eyes in abdomen absent. Abdominal neurochaetae narrowly-hooded. Abdominal notopodial tori not forming complete cinctures around the body (cinctures interrupted in middle region of each segment for 1/2 of its width, dorsally and ventrally). Avicular abdominal uncini with one row of two teeth above the main fang, breast well developed and handle minute ( Figs 23F , 39C–D ). Pygidium unknown. Tube not preserved.

Etymology. The name of this species is in honor of Richard C. Brusca (Arizona-Sonora Desert Museum), in recognition of his legacy to the knowledge of marine invertebrates, biogeography and conservation of the Gulf of California. The species-group name is a noun in the genitive case ( ICZN 1999, Art. 31.1.2).

Remarks. Myxicola is a genus composed of 18 valid species ( Darbyshire 2023, Putignano et al. 2023, 2024). Until few years ago, the type species, Myxicola infundibulum ( Montagu, 1808) was considered cosmopolitan, mostly due to the synonym of many other taxa under that name. It has been considered as an anthropogenically introduced species in some regions ( Darbyshire, 2023). For the Mediterranean Sea only, Putignano et al. (2023) recovered and named four new species previously recognized as M. infundibulum .

Regarding the genus Myxicola in North America, there are two recent contributions re-establishing M. conjuncta Bush, 1905 , M. affinis Bush, 1905 , M. glacialis Bush, 1905 and M. pacifica Johnson, 1901 for the Pacific Ocean, thus all four were considered valid species ( Putignano et al. 2023, 2024), while M. monacis Chamberlin, 1919 was regarded as a junior synonym of M. affinis ( Putignano et al. 2024) . In addition, specimens from the Gulf of Maine originally identified as Myxicola infundibulum were found to belong to two new species: Myxicola bushae Putignano, Langeneck & Giangrande, 2024 and M. boki Putignano, Langeneck & Giangrande, 2024 .

Myxicola infundibulum has also been also reported in the Mexican Pacific but a revision of these records is also needed (see Tovar-Hernández & Fitzhugh, 2021, and references therein). From the TALUD Project no species of Myxicola has been reported (see Méndez, 2006, 2007, 2009, 2012, 2013). Here we recognize two new species of Myxicola from the Gulf of California based on an unique combination of features. The first one from shallow water (3 m depth) in the southern Gulf of California ( Myxicola bruscai sp. nov.) and the second one from deep-sea samples of the TALUD Project, in depths of 319–681 m in the northern Gulf of California (see their formal description below).

Myxicola bruscai sp. nov., has a unique combination of features: 1. Subdistal radiolar eyes composed and paired. 2. Two glandular ridges (on chaetigers 1 and 2). 3. Lateral collar margins with a deep groove reaching next chaetiger. 4. Glandular longitudinal bars in posterior thoracic and abdominal segments. 5. Dorsal lips without radiolar appendages, and 6. Abdominal notopodial tori not forming complete cinctures around the body (cinctures interrupted in middle region of each segment for 1/2 of its width, dorsally and ventrally).

In addition to Myxicola bruscai sp. nov., only two other species of Myxicola are known with subdistal radiolar eyes: Myxicola ommatophora Grube, 1878 (from the Philippines) and Myxicola nana Capa & Murray, 2015 (from Lizard Island, Australia). These species differ from Myxicola bruscai sp. nov., in the following aspects. In M. nana and M. ommatophora the anterior ventral lobe is low and rounded, whereas in M. bruscai sp. nov., it is long and triangular. The palmate membrane extends 3/4 of the radiolar length in M. bruscai sp. nov., and M. ommatophora whereas in M. nana it occupies only 1/3 of the radiolar length. In addition, M. bruscai sp. nov., present two glandular ridges: on chaetigers 1 and 2, respectively (only one glandular ridge on chaetiger 2 in M. nana and M. ommatophora ). Glandular longitudinal bars in posterior thoracic and abdominal segments are only present in M. bruscai sp. nov., (absent in M. nana and M. ommatophora ). Myxicola nana has red, lateral eyespots on abdominal segments (absent in M. bruscai sp. nov., but presence/absence unknown in M. ommatophora ).

When comparing with the species of Myxicola recognized from the Pacific side of North America by Putignano et al. (2023, 2024), radiolar eyes are only known in M. bruscai sp. nov. Thoracic interramal eyes were reported as present from chaetiger 4 in M. affinis , from chaetiger 5 in M. conjuncta Bush, 1905 , and poorly visible in M. pacifica Johnson, 1901 without indications on which chaetiger these eyes are located ( Table 3). In contrast, M. glacialis Bush, 1905 and M. bruscai sp. nov., lack thoracic interramal eyes. Lateral eyes in abdomen are present in a dorsal position in M. affinis and M. conjuncta , present but poorly visible in M. pacifica , whereas these are absent in M. bruscai sp. nov. ( Table 3). Dorsal lips with long radiolar appendages are present only in M. affinis and in the new species described below from the TALUD project; dorsal lips with remarkably short radiolar appendages were reported in M. conjuncta and M. pacifica ; and dorsal lips without radiolar appendages are reported in M. glacialis and M. bruscai sp. nov. There are also minor differences in the shape, length and presence/absence of lateral flanges on radiolar tips ( Table 3). A comparison of M. bruscai sp. nov., and the second new species from deep-sea samples of the TALUD Project is presented below.

Abiotic conditions. The specimen of M. bruscai sp. nov., was collected in 3 m deep. No other environmental data available.

Distribution. Southern Gulf of California, Mexico.

Figures

FIGURE 22. Myxicola bruscai sp. nov. A) Body, dorsal view, B) anterior thoracic segments, dorso-lateral view, C) same, ventral view, D) abdominal segments, dorso-lateral view, E) anterior thoracic segments, dorsal view, F) same, lateral view, G) thoracic and abdominal transition, lateral view with arrows pointing to glandular bars. Abbreviations: gr1—glandular ridge on chaetiger 1, gr2—glandular ridge on chaetiger 2, d—dorsum, v—ventrum. Scale bars: A) 5 mm, B–C, E–F) 2 mm, D, G) 1.5 mm. A–G: holotype UANL-8273.

FIGURE 23. Myxicola bruscai sp. nov. A) Radiolar compound eyes, B, D, E) details of eyes, C) radiolar flanges and radiolar skeleton, F) abdominal uncini, G) elongate, narrowly hooded chaeta, H) acicular thoracic uncini. Abbreviations: fl—flange, pm—palmate membrane. Scale bars: A–C) 200 μm, D) 50 μm, E) 100 μm, F) 20 μm, G) 10 μm, H) 5 μm. A–H: holotype UANL-8273.

FIGURE 24. Myxicola bruscai sp. nov. A–B) Distal half of branchial crown showing tips, palmate membrane and subdistal eyes pointed with arrows, C–D) dorsal lips, from right and left lobe of branchial crown, respectively. C) Stained with methyl green. Abbreviations: dl—dorsal lip, pm—palmate membrane. Scale bars: A–B) 3 mm, C–D) 1 mm. A–D: holotype UANL- 8273.

FIGURE 39. Line drawings of chaetae and uncini. A–B, F–G, K, Q, T–U, X) Thoracic chaetae. C, H, L, R, W, Z) Thoracic uncini. D, I, N–O, S, V, Z1) Abdominal uncini. E) Companion chaeta. J) Abdominal chaeta. M, Y) Bayonet chaetae. A–E) Bispira beatrizae sp. nov. F–J) Bispira nunezi sp. nov. K–P) Chone tamai sp. nov. Q–S) Claviramus villalobosi sp. nov. T–W) Euchone nmercedesae sp. nov. X–Z1) Jasmineira agustinae sp. nov. Scale bar: 30 μm.

FIGURE 40. Line drawings of chaetae and uncini. A, G–H, L–M, S) Thoracic chaetae. B, E, J, O, Q, T) Thoracic uncini. C–D, F, K, P, U) Abdominal uncini. I, N, R) Companion chaetae. A–D) Myxicola bruscai sp. nov. E–F) Myxicola dilianae sp. nov. G–K) Perkinsiana araceliae sp. nov. L–P) Perkinsiana nuriae sp. nov. Q–U) Potamethus pepei sp. nov. Scale bar: 30 μm.