Astrocladus goodingi

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

persistent identifier

http://treatment.plazi.org/id/03D88782-FFD6-FFA5-7896-FE9B60B7FE23

treatment provided by

Plazi

scientific name

Astrocladus goodingi
status

sp. nov.

Astrocladus goodingi  sp. nov.

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

Astrocladus tonganus  .— Cherbonnier & Guille, 1978: 14, Pl. II figs. 3–4. Non Astrocladus tonganus Döderlein, 1911: 77  , 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. 7–10View FIGURE 7View FIGURE 8View FIGURE 9View 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, CView FIGURE 7, 8A –BView 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, CView FIGURE 8).

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

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

Arms coiled, bifurcated at least 16 times ( Fig. 7A –BView FIGURE 7). Girdles complete between disc edge and first arm branch ( Fig. 9AView 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. 9AView FIGURE 9), those disappear toward the distal arm tip ( Fig. 9DView FIGURE 9). Oral surface of arms and oral frame covered with flat, smooth polygonal plates surrounded by rows of single, smaller plates ( Fig. 8DView FIGURE 8, 9B –CView FIGURE 9). Up to 5 arm spines, beginning just before third arm branch, with initially 1 or 2, then 5, glassy-tipped spines ( Fig. 9CView 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. 10AView FIGURE 10), approximately 6 articulations in the distal portion ( Fig. 10HView FIGURE 10). The articulations forming two parallel rows ( Fig. 10A, HView FIGURE 10). Each hooklet bears one inner tooth ( Fig. 10B –CView FIGURE 10). Lateral arm plates concave on distal and basal sides, the concavity deeper on distal side ( Fig. 10D –EView FIGURE 10). No perforations visible on lateral arm plates but simple nerve openings on oral-external side ( Fig. 10E –FView FIGURE 10) and on distal portion of the arms; articulations for hooklets only visible on oral surfaces ( Fig. 10HView 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. 10IView FIGURE 10). All vertebrae with hourglass-shaped streptospondylous articulations ( Fig. 11D –E, H –IView FIGURE 11). Depressions for tube feet openings in the distal part of oral-lateral side of vertebrae ( Fig. 11A, GView FIGURE 11). A pair of radial water canals opening on the lateral side of vertebrae, near depression of the tube feet ( Fig. 11A, GView FIGURE 11) and radial nerve canals opening inside oral furrows ( Fig. 11AView 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 –CView FIGURE 9); Five arm spines bearing 1–5 terminal glassy spinules ( Fig. 10IView FIGURE 10), present from third arm segment; Genital slits narrow and short, bordered abradially by a row of tall spines ( Fig. 9FView FIGURE 9); Girdle bands present from disc margin, and complete between first and second arm branch ( Fig. 9AView FIGURE 9); Arm surface, orally and between girdles covered with large polygonal plates, separated by narrow rows of small single plates ( Fig. 9AView FIGURE 9).

Distribution. Western Indian Ocean including Mayotte Island (type locality) and the Mozambique Channel.

USNM

Smithsonian Institution, National Museum of Natural History

Kingdom

Animalia

Phylum

Echinodermata

Class

Ophiuroidea

Order

Euryalida

Family

Gorgonocephalidae

Genus

Astrocladus

Loc

Astrocladus goodingi

Baker, Alan N., Okanishi, Masanori & Pawson, David L. 2018
2018
Loc

Astrocladus tonganus

Cherbonnier & Guille, 1978 : 14
Döderlein, 1911 : 77