Beatricella calidafornax Gómez 2021, sp. nov.
Creators: name: Gómez, Samuel
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Hexanauplia
Harpacticoida
Miraciidae
Beatricella
Beatricella calidafornax

description: Beatricella calidafornax sp. nov.
(Figs. 7–12)
urn:lsid:zoobank.org:act: D94080DF-76FE-4D05-AF12-7251716F325A
Type locality. Guaymas Basin, between San Pedro Nolasco Island and Tortuga Island, Gulf of California, Mexico; Talud X cruise, sampling station 15 (27.7°N, 111.6333°W); depth, 1,570 m; organic carbon content, 4.48%; organic matter content, 8.37%; sand, 4.49%; clay, 11.96%; silt, 84 %.
Specimens examined. One female holotype dissected and mounted onto eight slides (EMUCOP-110207.04); February 11, 2007; coll. S. Gómez.
Etymology. According to one of several theories, the name California comes from the Old Spanish Calit Fornay, an alteration of the Latin calida fornax, hot furnace. The specific epithet makes reference to the region where the species was found. It is to be treated as a noun in apposition.
Differential diagnosis (based on the female only). Stenheliinae: Beatricella. Caudal rami elongate, cylindrical, 5.7 times as long as wide, and as long as three last urosomites combined.Antennule seven-segmented, with aesthetasc on fourth and last segments. P1 EXP2 with inner seta. P2 EXP1 without inner seta. Outermost seta of P5 BENP well developed.
Description of female. Total body length measured from tip of rostrum to posterior margin of caudal rami, 540 µm; habitus pyriform, widest at posterior end of cephalothorax, tapering posteriad.
Prosome consisting of cephalothorax with fused first pedigerous somite, and second to fourth free pedigerous somites. Free pedigerous somites without expansions or spinular ornamentation; integument smooth, weakly sclerotized.
Urosome consisting of fifth pedigerous somite (first urosomite), genital double-somite (genital—second urosomite—and third urosomites fused), two free urosomites, and anal somite. Urosomites without expansions laterally nor dorsally; integument weakly sclerotized.
Genital double-somite with laterodorsal internal rib marking original division between second (genital) and third urosomite (Fig. 7A, C), completely fused ventrally (Fig. 7B); proximal half (genital somite) with dorsolateral spinules close to posterior margin, and with posterior sensilla as depicted; distal half (third urosomite) with two sets of dorsolateral spinules (Fig. 7A, C), without surface ornamentation ventrally except for two sensilla (Fig. 7B).
Fourth urosomite as in posterior half of genital double-somite.
Fifth urosomite without sensilla; with one set of dorsolateral spinules (Fig. 7A, C); ventrally with two sets of spinules (Fig. 7B).
Anal somite (Fig. 7A–C) three times as broad as long from dorsal view, two times as broad as long from ventral view; dorsally with row of spinules close to joint with caudal rami, and one pore on each side; anal operculum nearly straight, flanked by one sensilla on each side; ventrally with two pores on each side, medially cleft, with spinules close to insertion with caudal rami.
Caudal rami elongate, cylindrical, 5.7 times as long as wide, and as long as three last urosomites combined; each ramus with one subdistal pore ventrally; with small spinules close to insertion site of caudal seta II (Fig. 7A– C); with seven elements; seta I spine-like, ventral to seta II, the former visibly smaller, both arising subdistally on lateral margin; seta III ventral, subdistal, slightly longer than seta II; seta IV and V situated distally; seta VI issuing at inner distal corner; dorsal seta VII triarticulate at base, situated subdistally close to inner margin.
Rostrum (Fig. 8A) trapezoidal, not fused to cephalothorax, slightly longer than two first antennulary segments combined, slightly bifid, with two subdistal sensilla.
Antennule (Fig. 8A) seven-segmented; all segments smooth, except for spinular row on first segment. All setae smooth except for pinnate seta on first, second, third, and sixth segments; second and third segments each with one seta with fracture plane; sixth and seventh segments each with one articulated seta. Armature formula: 1(1); 2(11); 3(8); 4(5 + (1 + ae)), 5(3); 6(8); 7(4 + acro). Acrothek consisting of two setae and one slender aesthetasc fused at their bases.
Antenna (Fig. 8B). Coxa short, with some spinules at inner and outer margins. Allobasis as long as free endopodal segment, inner margin with small proximal spinules and long spinules on proximal third, with one pinnate abexopodal seta arising midway inner margin. Exopod three-segmented, issuing proximally; first and third segments longest, each about 4.3 times as long as wide, with lateral and apical spinules as shown; first segment with one subdistal pinnate seta; third segment with one lateral pinnate element and three distal setae, of which two fused basally; second segment shortest, about 1.5 times as long as broad, and about one fourth the length of last segment, without surface ornamentation, with one distal pinnate seta. Free endopodal segment elongate, inner margin with proximal row of small spinules, subdistally with curved row of strong spinules, with medial and subdistal fringe; armature consisting of two lateral spines and two accompanying setae, one inner distal geniculate spine, three distal geniculate spines (of which innermost shorter) and one slender seta, and one outer distal geniculate seta fused basally to shorter element.
Mandible (Fig. 9A–B) with relatively short coxa. Gnathobase wide; ventral distal corner produced into small sharp semi-hyaline process; with two strong bicuspidate teeth, several smaller bicuspidate teeth, some spinules, and one slender smooth element accompanied by pinnate seta. Basis elongate, with proximal constriction, tapering distally; with some minute spinules at proximal third; with three subdistal setae. Exopod arising from short pedestal, elongate, about three times as long as wide, and 0.4 times as long as basis, tapering distally; with two outer, two inner, and two apical slender setae, the latter fused basally. Endopod recurved, twisted over exopod (Fig. 9B); with three lateral setae, and five distal elements (two slender setae and two strong elements, and longest element fused to endopod and with hyaline flange in middle part).
Maxillule (Fig. 9C–D). Arthrite of praecoxa with two surface setae and eight bare distal elements (one of which a slender seta arising next to ventralmost spine), one spinulose dorsal spine, and one lateral spinulose recurved seta (Fig. 9D). Coxa with spinular row and three setae, one of which pinnate. Basis with two endites; proximal endite with four, distal endite with three slender setae. Exopod and endopod fused basally, not fused to basis, onesegmented; endopod larger than exopod, with four setae; exopod small, with two setae.
Maxilla (Fig. 9E–F). Large syncoxa with outer spinules as shown; with three endites (Fig. 9F); proximal endite smallest, bilobate, each lobe with two setae; middle and distal endites elongate, the latter slightly longer, with three elements each. Basis drawn out into strong claw, additionally with strong spinulose spine and two slender setae. Endopod small, 1.5 times as long as wide, with six slender setae (one arising basally, one medially, and four apically).
Maxilliped (Fig. 9G) subchelate. Syncoxa rectangular, about 1.5 times as long as wide; with long inner spinules; with one bare and two spinulose strong elements, of which bare seta and one spinulose element more proximal and both at the same level, the other arising distally from long pedestal. Basis shorter than syncoxa, oval; with slender outer spinules, with one anterior and one posterior inner spinular row as depicted, and two slender distal setae. Endopod one-segmented, slender, with one claw-like element and one seta.
P1 (Fig. 10A). Basis with inner and outer spine, with small strong spinules between rami, and with comparatively slender spinules at bases of outer and inner spine, with long slender inner spinules. Exopod three-segmented, slightly shorter than endopod; first segment longest, third segment shortest, length ratio of EXP1–EXP3 1, 0.8, 0.7; with spinular ornamentation as shown; first segment without, second segment with inner seta, third segment with four elements in all. Endopod three-segmented, ENP1 reaching middle of EXP2, about 0.7 times as long as ENP2 and ENP3 combined; with outer and distal spinular ornamentation as shown; with one strong pinnate inner seta arising at distal third; ENP2 and ENP3 visibly slenderer, the former with one inner seta and outer spinules, the latter with few subdistal outer spinules and three apical elements.
P2 (Figs. 10B, 12A). Intercoxal sclerite not transversely elongate; trapezoidal; with strong pointed process on distal outer corners; without surface ornamentation (Fig. 12A). Coxa massive, square, with some outer spinules proximally and subdistally, with pore close to inner distal corner. Basis with outer setiform element and strong acute inner process, the latter reaching proximal fourth of ENP1 and with slender spinules at its base. Exopod threesegmented, reaching slightly beyond ENP2; EXP1 longest, EXP2 shortest, length ratio of EXP1–EXP3 1, 0.8, 0.9; EXP1 and EXP2 with outer acute distal process, with outer distal pore, with longitudinal row of outer spinules and with inner distal frill, EXP1 without, EXP2 with inner seta; EXP3 with small outer spinules proximally, with two inner and two apical setae, and three outer spines. Endopod three-segmented, noticeably longer than EXP; ENP1– ENP3 length/width ratio 1.6, 2.5, 4.1; ENP1 with strong outer spinules and with subdistal outer pore, with inner and outer acute processes, the former larger and with inner minute spinules, with one slender short inner seta issuing midway inner margin of segment; ENP2 with comparatively smaller outer spinules, with inner distal frill and two inner setae of which proximalmost visibly shorter; ENP3 with small outer spinules and with proximal inner pore, with one inner seta, two inner apical elements and one outer distal spine, with outer distal process and two additional smaller processes flanking two innermost apical elements.
P3 (Figs. 11A, 12B). Intercoxal sclerite not transversely elongate; trapezoidal; wider than in P2; with strong pointed process on distal outer corners; without surface ornamentation (Fig. 12B). Coxa squared; with spinules close to proximal and distal outer corners; with distal outer pore. Basis with outer seta, with pointed inner process smaller than in P2 and with slender spinules at its base, with minute spinules at the base of ENP. Exopod threesegmented, reaching proximal third of ENP3; EXP2 shortest, EXP1 and EXP3 longest, length ratio of EXP1–EXP3 1, 0.7, 1; EXP1 and EXP2 with outer acute distal process, with longitudinal rows of outer spinules and with inner distal frill, each with subdistal outer pore, with one inner seta each; EXP3 with minute outer spinules proximally, without pore, with three inner setae, two apical elements, and three outer spines. Endopod three-segmented, slightly longer than EXP; ENP1 shortest, ENP3 longest, length ratio of ENP1–ENP3 1, 1.1, 1.5; ENP1 with short outer distal process, with minute inner distal spinules, and with inner slender seta; ENP2 with spinular ornamentation as in previous segment, with inner pinnate stiff seta; ENP3 with small outer spinules, with one proximal inner slender seta, one medial inner pinnate stiff element, and one subdistal long inner seta, of which the latter thickest, two distal setae and one outer distal spine; acute processes flanking outer spine and two distal innermost setae.
P4 (Figs. 11B, 12C). Intercoxal sclerite not transversely elongate; trapezoidal; smaller than in P3; with strong pointed process on distal outer corners; without surface ornamentation (Fig. 12C). Coxa squared; ornamented as in P3. Basis as in P3, but inner process smaller. Exopod three-segmented, slightly longer than ENP; length ratio of EXP1–EXP3 1, 0.9, 1.1; EXP1 and EXP2 with outer distal process less developed than in P3, with longitudinal row of small outer spinules, with subdistal outer pore, with inner distal frill, and with inner seta; EXP3 with subdistal outer pore, with three inner setae, two apical elements, and three outer spines. Endopod three-segmented, shorter than EXP; ENP1 shortest, ENP3 longest, length ratio of ENP1–ENP3 1, 1.1, 1.3; ENP1 with strong outer spinules, without pore, with short outer distal process, with inner long stiff pinnate element; ENP2 as in previous segment except for slender inner seta and noticeably larger outer distal process; ENP3 with subdistal pore and some outer spinules, with two inner setae, two inner apical elements, and one outer apical spine, with short acute processes flanking outermost distal spine and two innermost distal elements.
Setal formula of swimming legs as follows:
P1P2P3P4EXP0,1,0220,1,2231,1,3231,1,323ENP1,1,1111,2,1211,1,3211,1,221
P5 (Fig. 8C). Baseoendopod pentagonal, with five setae, innermost and outermost setae shortest, all setae normal. Exopod oval, with some outer proximal spinules, with six setae, of which apical medial seta shortest.
P6 (Fig.7B–C) minute flap covering ventrolateral genital aperture,fused to somite, without surface ornamentation, with one slender seta.
Male. Unknown.
Remarks and discussion. The genus Beatricella was reinstated by Mu & Huys (2002) to reallocate Delavalia aemula Scott, 1893 and one species inquirenda, Stenhelia aemula sensu Marinov (1977). According to Mu & Huys (2002: 203), Beatricella does not display any of the seven synapomorphies for Stenhelia and Anisostenhelia, but can be defined upon three apomorphies: 1) male P2 ENP2 drawn out into sigmoid finely pinnate process and outer margin with row of long spinules, 2) P4 ENP1 with very long stout seta, and 3) the male P5 EXP incorporated in baseoendopod and outermost seta modified into strong spine. According to Mu & Huys (2002), the sigmoid process on the male P2 ENP2 of Beatricella is an apomorphy for the genus. However, the apomorphic status of the long stout inner seta on P4 ENP1 and the fused male P5 EXP and BENP with outermost element modified into a strong spine is uncertain as it is shared by some other stenheliins (see Gómez & Cruz-Barraza 2021).
The new species proposed here was attributed to the genus Beatricella by the combination of its three-segmented P1 ENP, primitive armature formula of P2 EXP3 (with two inner setae; armature formula 223) and P3 EXP3 (with three inner setae; armature formula 323), and presence of normal setae only on the endopodal lobe of P5. Mu & Huys (2002) suggested that the lack of an inner seta on P1 EXP2 could be a potential synapomorphy for Beatricella, Stenhelia and Anisostenhelia, but also Lonchoeidestenhelia. However, the presence of an inner seta on P1 EXP 2 in B. calidafornax sp. nov. seems to confirm that the lack of an inner seta on P1 EXP 2 in B. aemula is likely the result of a secondary loss and cannot be regarded as synapomorphic for Beatricella, Lonchoeidestenhelia, and Stenhelia - Anisostenhelia. On the other hand, B. calidafornax sp. nov. is similar to Itostenhelia, Willenstenhelia, Wellstenhelia, and Wellstenvalia in the retention of one inner seta on P1 EXP2. It is similar also to A. asetosa in the loss of the inner seta on P2 EXP1. Interestingly, A. asetosa shares the armature formula of P2 EXP (0,1,123) with Willenstenhelia.
The description of the new species proposed herein confirms that the caudal seta I of Beatricella is spine-like and this condition is shared, at least, with Anisostenhelia, Cladorostrata, Itostenhelia, Lonchoeidestenhelia, most species of Wellstenhelia and Me. papuaensis, and some species of Delavalia (see Gómez & Cruz-Barraza 2021).
The male of B. calidafornax sp. nov. remains unknown, but this species can be readily separated from B. aemula by the relative length of caudal rami (as long as anal somite in B. aemula, but as long as three last urosomites combined in the new species), number of segments of the female antennule (eight segments in B. aemula, but seven segments in the new species), armature complement of P1 EXP2 (without inner seta in B. aemula, but with inner seta in B. calidafornax sp. nov.), P2 EXP1 (with inner seta in B. aemula, but without inner armature in the new species), and relative length of outermost seta on female P5 endopodal lobe (very small in B. aemula, but well developed in the Mexican species).
description: Published as part of Gómez, Samuel, 2021, On some deep-sea Stenheliinae from the Gulf of California and the west coast of the Baja California Peninsula (Mexico): Pseudostenhelia bathyalis sp. nov., and Beatricella calidafornax sp. nov. (Copepoda: Harpacticoida: Miraciidae), pp. 151-170 in Zootaxa 5051 (1) on pages 161-169, DOI: 10.11646/zootaxa.5051.1.11, http://zenodo.org/record/5563475