Ceramaster fortis, Mah, 2025

Ceramaster fortis n. sp.

Figures 10A–F

Material Examined. Holotype. WAM Z110161 About WAM . Gascoyne Marine Park, Western Australia, Indian Ocean , 22º 0' 0.1656" S, 113º 44' 13.1316" E, 794.0 m. Coll. B. Alvarez, K. M. Naughton, K. Moore and C. Unteidt. 8 December 2022, Gascoyne 10055572. 1 wet spec. R = 10.8 r = 6.5 GoogleMaps

Etymology. The species epithet fortis is derived for the Latin for “strong”, alluding to this species’ particularly stout and well-developed skeleton.

Diagnosis. Body stout, thick, weakly stellate (R/r = 1.66), arms upturned, broadly triangular in shape. Disk large, interradial arcs weakly curved to straight. Abactinal plates tabulate. Each plate covered with polygonal, well-developed, coarse granules, 4–18 around periphery, angular, 3–20 present in central surface. Fasciolar grooves well developed. Superomarginal plates, 13–14 per side, 26–28 per interradius, surface covered with coarse, round granules, close-set approximately 3 count along a 1.0 mm line. Superomarginal surface completely covered with no bare region. Actinal region large, with up to 15 full series in chevron-like arrangement. Plate surface covered by large, coarse, round to polygonal granules. Furrow spines, 5 to 9. Subambulacral spines and granules in two to three irregularly arranged series. Subambulacral spines closely arranged, 4 to 5, two to three times as thick as the furrow spines,

Comments. A species that appears to be a member of the C. patagonicus group within Ceramaster based on the coarse and strongly angular granules present on the abactinal table, the well-developed granulation present on the marginal plates and the well-developed fasciolar grooves present among the abactinal plates. The skeleton in this species is heavily developed.

This species differs from C. patagonicus and Ceramaster australis H.E.S. Clark, 2001 in that the superomarginal surface is completely covered in granules, the distinct convex to raised bare patch present on the superomarginal plate surface in other species is absent. There are large angular granules present, especially on the periphery of the tabulate plates, 4 to 18 versus the smaller granules in C. patagonicus with 8 to 80 total. C. australis further differs in showing significantly smaller and differently shaped peripheral granules and much fewer superomarginal plates per interradius (n = 19 at R = 4.2) versus 26–28 (R = 10.8) in C. fortis n. sp. Superomarginal plates on C. australis are much more tumid, strongly convex in cross-section. C. fortis , displays greater numbers of furrow spines, 5 to 9 versus 3 to 4 on C. patagonicus .

C. fortis n. sp. is most similar to the South African Ceramaster trispinosus with which it shares the coarse abactinal and actinal granules, the granular cover over the superomarginal and inferomarginal plates, and the stout skeletal construction. It differs in having 5 to 9 furrow spines versus 3 furrow spines in C. trispinosus , which are much shorter than those of C. trispinosus . The subambulacral spines are much thicker and blockier than those of C. trispinosus .

Occurrence/Distribution. Gascoyne Marine Park, Western Australia, Indian Ocean , 794 m.

Description. Body stout, thick, weakly stellate (R/r = 1.66), arms upturned, broadly triangular in shape. Disk large, interradial arcs weakly curved to straight ( Fig. 10A, E).

Abactinal surface strongly tabulate, completely covered by closely abutted tabulate plates. Each plate covered with polygonal, well-developed, coarse granules, 4–18 around periphery, 3–20 present in central surface ( Fig. 10B, C). Approximately 2 count along a 1.0 mm line. Granules closely arranged, but evenly distributed on plate. Radial regions arched, interradial regions with shallow valleys. Abactinal plates more densely arranged interradially than on radial arm regions. Pedicellariae, elongate paddle-shaped, present on 40–50% of plates overall but with slightly higher numbers present on radial regions. When present pedicellariae located on central surface surrounded by granules. Fasciolar areas well-developed but especially so along proximal radial regions along arms. Madreporite pentagonal, strongly convex with well-developed sulci.

Marginal plates approximately 13–14 per arm side, 26 to 28 per interradius, with predominantly lateral facing ( Fig. 10A, D). Superomarginals quadrate in shape, surface flat becoming more convex distally adjacent to arm tip. Superomarginals offset with inferomarginals forming zigzag contact between them. Superomarginal plate surface covered with coarse, round granules, close-set approximately 3 counts along a 1.0 mm line ( Fig. 10D). Superomarginal and inferomarginal plate surfaces with 40–60 granules, quadrate to shield-shaped present in a single series around plate periphery. Central region with 100–300 round granules, present on superomarginal plates especially those interradially with granule number decreasing with smaller plate size distally along the arm. Pedicellariae, elongate paddle-shaped, 1 to 4, similar to those on abactinal surface present on a one or two of the total number of superomarginal plates per interradius. No bald spots. Inferomarginal contact with actinal intermediate region irregularly convex, especially interradially.

Actinal intermediate areas large, approximately 15 full series of actinal plates in chevron formation with multiple irregular series present interradially adjacent to the inferomarginal plate contact ( Fig. 10E). Individual plates quadrate proximally adjacent to adambulacral plate series becoming more irregularly polygonal in shape adjacent to contact with inferomarginal plates. A closely arranged cover of polygonal to round coarse granules, approximately 2 granules counted along a 1.0 mm line. Granules variably rounded to weakly pointed.

Adambulacral armature closely arranged, crowded. Furrow spines 5 to 9, proximalmost adambulacral plates with five, then increasing 7 to 9 distally then decreasing to approximately five adjacent to arm tip. Furrow spines, blunt, with quadrate tips, arranged in strongly palmate to straight series ( Fig. 10F). Spines quadrate to triangular in cross-section. A large space separating furrow spines from subambulacral spines. Subambulacral spines and granules in two to three irregularly arranged series. Subambulacral spines closely arranged, 4 to 5, two to three times as thick as the furrow spines, immediately adjacent to furrow spines with club-like blunt tips. Subsequent subambulacral spine series, 3 to 4, approximately half the height of the subambulacral spines but as thick as prior series, quadrate to triangular in cross-section. Subsequent granules on adambulacral plates, polygonal but identical in size with granules on adjacent actinal surface, more widely spaced.

Oral plate furrow spines 12–14, quadrate to polygonal in cross-section, blunt tipped ( Fig. 10E). Approximately 8 to 10 paired quadrate granules present along edge of each ridge adjacent to diastema. Oral plate surface with further 8–10 polygonal granules. First adambulacral plate with an elongate pedicellariae present adjacent to oral plate.

Cardiac stomach extended.