Scottolana tama Gómez, Yáñez-Rivera, García-Vázquez & Armenteros, 2024, sp. nov.

Scottolana tama sp. nov. urn:lsid:zoobank.org:act: 7C48B881-943C-4FEB-AE39-C9CD8F81950B (Figs. 2–11) Material examined. Ovigerous ♀ holotype preserved in alcohol (ICML-EMUCOP-020223-01), ♂ allotype preserved in alcohol (ICML-EMUCOP-020223-02), three ♀ paratypes dissected and mounted on six, 14, and eight slides (ICML-EMUCOP-020223-03–05), one ♂ paratype dissected and mounted on seven slides (ICML-EMUCOP-020223-06), five ♀, one ♂ CV, and three ♀ paratypes (ICML-EMUCOP-020223-07), and two ♀ paratypes (ICML-EMUCOP-020223-08) preserved in alcohol; holotype, allotype and paratypes ICML-EMUCOP-020223-05–07 from the type locality (stn 8, see below), paratype ICML-EMUCOP-020223-08 from stn 7 (see below); February 2, 2023; Leonardo García-Vázquez leg. Type locality. North-western Mexico, northern Sinaloa state, Ohuira Bay, stn 8 (25.64°N, 108.96°W), sand 57.26%, silt 25.67%, clay 17.08%, C org 2.84 %. Other sites. North-western Mexico, northern Sinaloa state, Ohuira Bay, stn 7 (25.66°N, 108.96°W; sand 16.23%, silt 59.54%, clay 24.22%, C org 2.24%); Ensenada del Pabellón lagoon, stn 4 (24.48°N, 107.65°W) [see Gómez Noguera & Hendrickx (1997)], clayish sediment, C org 1.29 µmol g-1. Additional material preserved in alcohol. North-western Mexico, northern Sinaloa state, Ohuira Bay: one CIII (ICML-EMUCOP-020223-09; stn 1; 25.61°N, 109.03°W; sand 67.07%, silt 23.79%, clay 9.14%, C org 1.07%), one ♀, one ♀ and one CV, and three ♀ and one ♂ (ICML-EMUCOP-020223-10–12; stn 2; 25.6°N, 109.02°W; sand 92.22%, silt 6.03%, clay 1.86%, C org 0.37%), three ♀, and three ♀ (ICML-EMUCOP-020223-13–14; stn 4; 25.62°N, 108.98°W; sand 16.52%, silt 53.61%, clay 29.87%, C org 3.36%), one ♀, and two ♀ (ICML-EMUCOP-020223-15–16; stn 5; 25.6°N, 108.98°W; sand 47.88%, silt 37.99%, clay 14.12%, C org 2.19%), one ♀ and one ♂, and one ♀ (ICML-EMUCOP-020223-17–18; stn 6; 25.56°N, 108.98°W; sand 27.34%, silt 49.06%, clay 23.60%, C org 2.37%), three ♀, and five ♀ and one ♂ (ICML-EMUCOP-020223-19–20; stn 7; 25.66°N, 108.96°W; sand 16.23%, silt 59.54%, clay 24.22%, C org 2.24%), and three ♀, one ♂, and one CV (ICML-EMUCOP-020223-21; stn 8; 25.64°N, 108.96°W; sand 57.26%, silt 25.67%, clay 17.08%, C org 2.84), collected in February, 2023; six ♀, two ♂, and two CV, and seven ♀ (ICML-EMUCOP-020623-05–06; stn 1; 25.61°N, 109.03°W; sand 71.68%, silt 21.48%, clay 6.84%, C org 0.93%), two ♀, and three ♀ (ICML-EMUCOP-020623-07–08; stn 3; 25.64°N, 109.0°W; sand 41.93%, silt 40.88%, clay 17.19%, C org 1.49%), three ♀ and one ♂ (ICML-EMUCOP-020623-09; stn 4; 25.62°N, 108.98°W; sand 20.77%, silt 53.54%, clay 25.68%, C org 2.89%), one ♀ (ICML-EMUCOP-020623-10; stn 5; 25.6°N, 108.98°W; sand 30.62%, silt 52.75%, clay 16.62%, C org 1.67%), one ♀, and two ♀ (ICML-EMUCOP-020623-11–12; stn 6; 25.56°N, 108.98°W; sand 15.37%, silt 58.58%, clay 26.06%, C org 2.58%), three ♀ (ICML-EMUCOP-020623-13; stn 8; 25.64°N, 108.96°W; sand 41.42%, silt 38.45%, clay 20.12%, C org 2.48%); June 2 2023; Leonardo García-Vázquez leg. Additional material dissected. North-western Mexico, central Sinaloa state, Ensenada del Pabellón lagoon: one ♀ (ICML-EMUCOP-010591-64) mounted on four slides; May 5, 1991 (see above for some environmental variables). Etymology. The species is dedicated to the fond memory of our friend and colleague Sergio “Tama” Rendón Rodríguez † (Instituto de Ciencias del Mar y Limnología). Differential diagnosis. Canuellidae. Caudal rami with seven setae arising (sub)distally of which one inner element (seta II) transformed into a strong spine with a conspicuous setule-like structure (tube-pore?). Antennule seemingly six-segmented, with second to fifth segments imperfectly separated. Antenna with eight-segmented exopod, and three-segmented endopod; EXP1–7 with one, EXP8 with four setae; ENP1 with two, ENP2 with four, ENP3 with seven elements. Mandibular EXP three-segmented, EXP1 with two, EXP2 with one, EXP3 with three elements; ENP two-segmented, ENP1 with three, ENP2 with eight setae. Maxillulary EXP one-segmented, with 11 setae. Maxillary ENP two-segmented. Maxilliped phyllopodial; syncoxa with one praecoxal seta, and three coxal endites bearing two, four and two setae, respectively; basis with two, ENP with 11 setae. Male P6 a triangular plate with one distal smooth seta, and genital area with two slender long elements with clawed distal part. Description of female. Habitus (Fig. 2A) semicylindrical; total body length measured from anterior tip of rostrum to posterior margin of caudal rami ranging from 860 µm to 1100 µm (mean= 1008.8 µm; n= 8), with maximum width at the posterior margin of cephalosome. General body shape largely as in S. antillensis. Rostrum (Fig. 5E) not fused to cephalosome; large, triangular, with rounded tip; with one subapical sensilla on each side; no pore detected. First pedigerous somite free; first to fourth pedigerous somites of about the same width, with parallel lateral margins; surface of prosomites covered with minute denticles, with smooth posterior hyaline fringes. Urosome (Figs. 2A, 3A, B) tapering posteriad, consisting of fifth pedigerous somite, genital somite and third urosomite fused dorsally and ventrally forming genital double-somite (the latter slightly longer than wide, with lateral internal cuticular band indicating former division between somites and with genital area (Fig. 3B) situated proximally in the middle of ventral surface), two free urosomites, and anal somite with rounded anal operculum and caudal rami; surface of urosomites covered with tiny denticles, with sensilla and pores as shown; hyaline posterior fringe of fifth pedigerous somite, genital double-somite, fourth and fifth urosomites plain, hyaline fringe of anal somite minutely incised and flanked by two transverse rows of spinules. Caudal rami (Fig. 3A, B) as long as fifth and anal somites combined, slightly conical, slightly tapering posteriad; inner and outer margins nearly straight; with seven setae arising (sub)distally, homology of setae difficult to determine, most probably as follows: seta I and II displaced ventrally on inner margin, the former short and slender, the latter transformed into a strong blunt spine with a conspicuous setule-like structure (tube-pore?) (Figs. 3B, 4); seta III long, displaced ventrally close to inner distal corner; seta IV dorsal to seta V, the former without, the latter with fracture plane; seta VI short and slender, close to seta V; dorsal seta VII biarticulate at base, close to inner distal corner. Female holotype with two multiseriate egg sacs with 11 eggs each. Antennule (Fig. 5A, B) presumably with six original segments. First segment unarmed, with two subdistal rows of long spinules ventrally; second to fifth segments imperfectly separated, with 28 setae in all of which eight biarticulate, and two (seemingly free) aesthetascs; sixth segment with 14 elements of which one biarticulate. Antenna (Fig. 5C, D) biramous. Basis unornamented. Exopod relatively shorter than endopod; eight-segmented; first-seventh segments with one, eighth segment with four pinnate elements. Endopod three-segmented; first segment with two, second segment with two medial and two distal setae as figured, third segment with six pinnate well-developed setae and one small, slender, bare element. Mandible (Fig. 6A, B) with well-developed gnathobase bearing multicuspidate teeth and one pinnate seta as shown. Basis large, with two inner subdistal pinnate setae. Exopod three-segmented, bent outwards, first and third segments shortest, middle segment longest; first segment with one proximal and one subdistal seta, second segment with one proximal element, third segment with three setae; all setae plumose. Endopod two-segmented; first segment larger, with three inner subdistal setae, second segment with eight distal elements as depicted. Maxillule (Fig. 6C–F) with praecoxa and coxa partially fused. Praecoxal arthrite with medial row of small spinules and with two surface setae, distally with eight spines and two setae as shown. Coxal endite with short row of subdistal spinules and six setae; with two long plumose epipodal setae. Basis with row of long inner spinules, seemingly with two ill-defined endites of which proximal with three, distal with five elements. Exopod large, slightly bent outwards, one-segmented; with five inner relatively short setae, five distal very long elements, and one outer reduced seta; all elements plumose. Endopod shorter than exopod, two-segmented; first segment larger, with five inner elements as shown; second segment with six plumose setae. Maxilla (Fig. 7A) with large praecoxa bearing two endites; proximal endite larger than distal, with three long pinnate elements and one small bare seta; distal endite with two pinnate setae. Coxa shorter than praecoxa; with two endites of which proximal somewhat shorter, each endite with subdistal small spinules and three setae as shown. Allobasis drawn out into strong unipinnate claw accompanied by five elements of which one a strong spinulose spine nearly as long as claw. Endopod two-segmented; first segment with five, third segment with four setae. Maxilliped (Fig. 7B) phyllopodial. Praecoxa and coxa fused forming syncoxa; with one —praecoxal— proximal seta, and thee —coxal— endites of which proximal with two (one unipinnate, one strongly spinulose), medial with four (two unipinnate, two strongly spinulose), distal with two unipinnate setae. Basis with slender long spinules along outer margin and small subdistal spinular ornaments as figured, with two unipinnate setae. Endopod one-segmented, as long as basis; with 11 setae arranged as follows: innermost element strongly spinulose, three pairs composed of one inner unipinnate seta and one strongly spinulose element each, and four outer plumose elements. P1 (Fig. 8A) with intercoxal sclerite transversely elongate. Coxa and basis with spinular ornamentation as figured, the former with inner long pinnate seta, the latter with outer pinnate seta