Astrocladus goodingi, Baker & Okanishi & Pawson, 2018

Baker, Alan N., Okanishi, Masanori & Pawson, David L., 2018, Euryalid brittle stars from the International Indian Ocean Expedition 1963 - 64 (Echinodermata: Ophiuroidea: Euryalida), Zootaxa 4392 (1), pp. 1-27 : 11-14

publication ID	https://doi.org/ 10.11646/zootaxa.4392.1.1
publication LSID	lsid:zoobank.org:pub:B6A80A66-E868-4578-A5E5-655E0F18AA84
DOI	https://doi.org/10.5281/zenodo.6486043
persistent identifier	https://treatment.plazi.org/id/03D88782-FFD6-FFA5-7896-FE9B60B7FE23
treatment provided by	Plazi
scientific name	Astrocladus goodingi
status	sp. nov.

Treatment

Astrocladus goodingi View in CoL sp. nov.

( Figs. 7A–C View FIGURE 7 , 8–11 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURE 11 )

Astrocladus tonganus View in CoL .— Cherbonnier & Guille, 1978: 14, Pl. II figs. 3–4. Non Astrocladus tonganus Döderlein, 1911: 77 View in CoL , 107, pl. 9 fig.8.

Material Examined. Holotype USNM 1072479, Anton Bruun Cruise 9, Indian Ocean, Comoro Islands, Mayotte Island, Bandeli Reef, 12° 54’S, 45° 16.5’E, inner side of reef, depth approximately 1 m, 23–26 November 1964. Collected by R.U. Gooding (RU-297), 1 specimen, disc diameter 15 mm ( Figs. 7–10 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 ).

Other material examined. Three specimens from localities in the northwest and south of Madagascar, identified by Cherbonnier & Guille 1978 as Astrocladus tonganus Döderlein (sent to ANB by the late Dr A. Guille, specimens now in Muséum National d’Histoire Naturelle, Paris). The three specimens were referenced by Baker (1980, p. 64). Their current catalogue numbers were unavailable.

Etymology. Named for the collector, the late Dr R.U. “Judge” Gooding of Barbados; our friend and colleague.

Diagnosis. Disc and radial shields with tubercles bearing 2–8 glassy spines; five arm spines bearing 1–5 glassy spinules, present from third arm segment; girdle bands present from disc margin; arm areas between girdles and orally with large polygonal plates, separated by narrow rows of small single plates. Genital slits bordered abradially by a row of tall spines.

Description of the holotype. External morphology. Aboral disc depressed at center, aborally with scattered small <0.3 mm diameter tubercles bearing 2–8 glassy spines averaging 86 µm in length, on a dense background of small, low granules ( Fig. 7A, C View FIGURE 7 , 8A–B View FIGURE 8 ).

Radial shields prominent, narrow (ratio length to breadth 1:8), slightly divergent, not meeting centrally, covered with small (0.1 mm diameter) tubercles bearing 1–5 glassy spines interspersed with flat plates ( Fig. 8A, C View FIGURE 8 ).

Oral disc covered by plate-shaped external ossicles, teeth large, spear-shaped; oral papillae small, spiniform ( Fig. 8E View FIGURE 8 ). One madreporite on the inner border of the soft interbrachium ( Fig. 8E View FIGURE 8 ).

Oral interradii with a close cover of pustules and scatted large tubercles, a few bearing spines ( Fig. 8F View FIGURE 8 ). Genital slits narrow and short (0.25 x 2.0 mm), bordered abradially by a row of tall spines ( Fig. 8F View FIGURE 8 ).

Arms coiled, bifurcated at least 16 times ( Fig. 7A–B View FIGURE 7 ). Girdles complete between disc edge and first arm branch ( Fig. 9A View FIGURE 9 ), girdle hooklets with one secondary tooth. Between girdles, arms have a few spines basally, but mostly large flat polygonal plates, bearing low smooth knobs ( Fig. 9A View FIGURE 9 ), those disappear toward the distal arm tip ( Fig. 9D View FIGURE 9 ). Oral surface of arms and oral frame covered with flat, smooth polygonal plates surrounded by rows of single, smaller plates ( Fig. 8D View FIGURE 8 , 9B–C View FIGURE 9 ). Up to 5 arm spines, beginning just before third arm branch, with initially 1 or 2, then 5, glassy-tipped spines ( Fig. 9C View FIGURE 9 ). Five arm segments to first branch, 4 to next branch.

Ossicle morphology. Hooklet-bearing plates possessing approximately 16 tubercle-shaped articulations for hooklets in the basal portion of the arm ( Fig. 10A View FIGURE 10 ), approximately 6 articulations in the distal portion ( Fig. 10H View FIGURE 10 ). The articulations forming two parallel rows ( Fig. 10A, H View FIGURE 10 ). Each hooklet bears one inner tooth ( Fig. 10B–C View FIGURE 10 ). Lateral arm plates concave on distal and basal sides, the concavity deeper on distal side ( Fig. 10D–E View FIGURE 10 ). No perforations visible on lateral arm plates but simple nerve openings on oral-external side ( Fig. 10E–F View FIGURE 10 ) and on distal portion of the arms; articulations for hooklets only visible on oral surfaces ( Fig. 10H View FIGURE 10 ). Arm spines in the basal portion of the arm ovoid and having one secondary point, approximately one-third length of the height of the spine ( Fig. 10I View FIGURE 10 ). All vertebrae with hourglass-shaped streptospondylous articulations ( Fig. 11D–E, H–I View FIGURE 11 ). Depressions for tube feet openings in the distal part of oral-lateral side of vertebrae ( Fig. 11A, G View FIGURE 11 ). A pair of radial water canals opening on the lateral side of vertebrae, near depression of the tube feet ( Fig. 11A, G View FIGURE 11 ) and radial nerve canals opening inside oral furrows ( Fig. 11A View FIGURE 11 ).

Remarks. The genus Astrocladus contains 10 nominal species, of which five are now know from the Indian Ocean or nearby: A. hirtus Mortensen , A. euryale (Retzius) , A. exiguus (Lamarck) , A ludwigi (Döderlein) , and A africanus Mortensen. Adding a further species to this fauna may seem an unnecessary complication, especially given the intra-species variations and similarity in morphology of A. euryale and Astrodendrum capensis ( Mortensen, 1933b) as noted by A. M. Clark (1974) in her account of echinoderms from Southern Africa. We have, however, examined the descriptions of all the Astrocladus species, and cannot reconcile the Comoro and Madagascar specimens with any known taxon.

Cherbonnier & Guille (1978) referred five specimens of an Astrocladus collected in northwestern and southern Madagascar, to A. tonganus Döderlein, 1911 a species previously known only from the Pacific Ocean near the Tonga Islands. Baker (1980, p. 64) compared some of their material with A. tonganus from the Pacific type locality, and found that it represented a “species allied to A. hirtus ”. The Cherbonnier & Guille (1978) material is referred here to A. goodingi sp. nov. A. tonganus has a disc covering of conical tubercles bearing 1–2 glassy spines, but there the external similarity with A. goodingi ends: the arms of A. tonganus are covered above with flat plates and pointed tubercles and below with closely set small plates, the girdle belts are continuous only after the 7th arm bifurcation, and the genital slits are not bordered by tall spines. A. hirtus from “Natal or Mozambique ”, is perhaps closer to A. goodingi sp. nov., but differs mainly in that it has fewer glassy spines on the disc tubercles, radial shields bearing slender papillae, and complete belts of girdle hooklets from the 6th arm bifurcation ( Mortensen, 1933b; A. M. Clark & Courtman-Stock, 1976).

The distinguishing features of A goodingi sp. nov. are: Disc and radial shields bearing conical tubercles with 2–8 terminal glassy spines ( Fig. 9B–C View FIGURE 9 ); Five arm spines bearing 1–5 terminal glassy spinules ( Fig. 10I View FIGURE 10 ), present from third arm segment; Genital slits narrow and short, bordered abradially by a row of tall spines ( Fig. 9F View FIGURE 9 ); Girdle bands present from disc margin, and complete between first and second arm branch ( Fig. 9A View FIGURE 9 ); Arm surface, orally and between girdles covered with large polygonal plates, separated by narrow rows of small single plates ( Fig. 9A View FIGURE 9 ).