Astrodendrum capense ( Mortensen, 1933 )

Okanishi, Masanori & Fujita, Toshihiko, 2018, A taxonomic review of the genus Astrodendrum (Echinodermata, Ophiuroidea, Euryalida, Gorgonocephalidae) with description of a new species from Japan, Zootaxa 4392 (2), pp. 289-310 : 301-302

publication ID	https://doi.org/ 10.11646/zootaxa.4392.2.4
publication LSID	lsid:zoobank.org:pub:C1A8F758-D41A-404C-A5C4-6CBC476EA324
DOI	https://doi.org/10.5281/zenodo.5998501
persistent identifier	https://treatment.plazi.org/id/2526AA33-FF94-417A-D9C2-E9A0FD64D40F
treatment provided by	Plazi
scientific name	Astrodendrum capense ( Mortensen, 1933 )
status

Treatment

Astrodendrum capense ( Mortensen, 1933) View in CoL

( Figs 8 View FIGURE 8 , 9 View FIGURE 9 )

Astroconus capensis Mortensen, 1933 . 285–288, fig. 19a–e;— A. M. Clark & Courtman-Stock, 1976. 132. Astrodendrum View in CoL capensis— Baker, 1980. 58; Alva & Vadon, 1989. 831, fig. 1c–d.

Type materials. ZMUC OPH-80 , holotype, collected by Fisheries Survey, northeastern Durban , South Africa, 29˚51.00’S, 31˚28.00’E, 415 m deep, August 1929 ( Fig. 1 View FIGURE 1 ).

Diagnosis. External ossicles granular, fully in contact and large conical, separated on aboral disc; external ossicles plate shaped, fully in contact and conical, separated on interradial lateral disc; external ossicles plateshaped, fully in contact on oral surface of disc; bulges of lateral edges of proximal portion of arms absent; 2 or 3 terminal projections on each arm spine in proximal portion of arm; 1 or 2 secondary teeth on each hook-shaped arm spine in distal portion of arm.

Description of holotype. Disc. Disc five-lobed with notched interradial edges, 60 mm in disc diameter ( Fig. 8A View FIGURE 8 ). Radial shields tumid ( Figs 10A, C, D View FIGURE 10 ). Aboral disc entirely covered by small granular external ossicles, fully in contact, and large conical external ossicles, separated and scattered on radial shields and lateral marginal edge of disc ( Fig. 8A, B, F View FIGURE 8 ). Granular external ossicles approximately 100–150 µm in length ( Fig. 8E, F View FIGURE 8 ). The large conical external ossicles approximately 400–1300 µm in length on radial shields and 350–750 µm in length at lateral marginal edge of disc ( Fig. 8F View FIGURE 8 ). Radial shields completely concealed by external ossicles, bar-like, approximately 12 mm in length, 3 mm in width, and almost reaching disc center ( Fig. 8C View FIGURE 8 ). Oral surface of disc covered by flat, polygonal plate-shaped external ossicles, fully in contact, approximately 300–450 um in length ( Figs 8G, H View FIGURE 8 , 11A View FIGURE 11 ). Oral shields, adoral shields, oral plates and ventral arm plates completely concealed by external ossicles ( Fig. 8G View FIGURE 8 ). Uniformly flat and spiniform teeth on dental plates, approximately 2.5–6 mm length and approximately 10 on each dental plate ( Fig. 8H View FIGURE 8 ). Smaller acute and spine formed teeth on edge of each oral plate, approximately 1.2–2.0 mm in length and 12–14 in number ( Fig. 8H View FIGURE 8 ). Interradial surface of lateral disc covered by flat plate-shaped external ossicles, fully in contact, and conical external ossicles, separated and scattered ( Fig. 9B View FIGURE 9 ). Plate-shaped external ossicles approximately 100 um in length and granular external ossicles approximately 100–150 um in length ( Fig. 9B View FIGURE 9 ). Two genital slits (4.6 mm long and 0.6 mm wide) in each interradius ( Fig. 8B View FIGURE 8 ). Minute spinule ossicles along genital slits, 70–80 µm in length ( Fig. 8B, E View FIGURE 8 ). One inconspicuous large, elliptical madreporite situated on an oral interradius, approximately 5 mm in length and 1.5 mm in height ( Fig. 8G View FIGURE 8 ).

Arms. Arms five, branching at least 8 times but further branches interminate because of entanglement of arms ( Fig. 8A, B View FIGURE 8 ). First branch occurring outside of disc ( Fig. 8B View FIGURE 8 ). On the proximal portion of the arm, the width and height almost equal, 6.5 mm with an arched aboral surface and flattened oral surface ( Fig. 8B View FIGURE 8 ). Arms tapering gradually towards arm tip ( Figs 10B View FIGURE 10 ; 11C, D, F. F–H).

On aboral and lateral surface of the proximal portion of arm, each arm segment covered by plate-shaped external ossicles, fully in contact, approximately 150–200 µm in length ( Fig. 9C View FIGURE 9 ). Hooklet-bearing plates inconspicuous, approximately 300 µm in length and separated, but not carrying hooklets before third branch ( Fig. 9C View FIGURE 9 ), in contact and forming transverse rows after fourth branch ( Fig. 9D View FIGURE 9 ). Throughout the arm, secondary hooklet present on hooklets. In middle portion of arm, aboral and lateral surfaces covered by plate-shaped external ossicles, fully in contact, approximately 120 µm in length ( Fig. 9D, G View FIGURE 9 ). Oral surface of proximal portion of arms covered by flat, polygonal plate-shaped external ossicles, fully in contact, approximately 280–650 µm in length ( Fig. 9E View FIGURE 9 ). In middle portion of arm, oral surfaces covered by flat, slightly tumid plate-shaped external ossicles, slightly in contact, approximately 100–180 µm in length ( Fig. 9F View FIGURE 9 ). Those external ossicles disappearing on distal portion of the arms ( Fig. 9H View FIGURE 9 ). Throughout arm, lateral and ventral arm plates completely concealed by skin or external ossicles ( Fig. 8C–H View FIGURE 8 ). Tentacle pores small and almost invisible in external view ( Fig. 8G View FIGURE 8 ). The first to third tentacle pores with no arm spine; fourth pores occasionally with 2 arm spines, fifth and subsequent pores with 3 (rarely 4) spines ( Fig. 9F, G View FIGURE 9 ). In distal portion of the arm, the number of arm spines decreasing gradually to 1 toward arm tip ( Fig. 9H View FIGURE 9 ). Arm spines on proximal portion of the arms ovoid, carrying 2 or 3 terminal projections. Innermost arm spines one-fourth the length of the corresponding arm segment, and outer spines two-thirds the length of inner spines ( Fig. 9E View FIGURE 9 ). Arm spines on middle portion of arm cylindrical, carrying 2 terminal projections ( Fig. 9F View FIGURE 9 ). Innermost arm spines half of length of corresponding arm segments, gradually decreasing in length to one-sixth length of corresponding arm segments toward outer spine ( Fig. 9F, G View FIGURE 9 ). In the distal portion of arms, arm spines transforming into hooks with 2 secondary teeth, approximately two-thirds length of the corresponding arm segments ( Fig. 9H View FIGURE 9 ).

Color. Uniformly white, interradial disc areas slightly darker ( Fig. 8A, B View FIGURE 8 ).

Distribution. REPUBLIC OF SOUTH AFRICA. Off Durban, southeastern Africa (type locality, Mortensen, 1933). NAMIBIA. West off Namib-Naukluft National Park, southwestern Africa ( Alva &Vadon, 1989; Olbers, 2016). Depth range 161–478 m ( Fig. 1 View FIGURE 1 ).

Remarks. Astrodendrum capense is related to A. elingamita in possessing small granular external ossicles, fully in contact on aboral disc. A. capense and A. elingamita can be distinguished by absence/presence of large conical spines on radial shields and the maximum number of secondary teeth on hook-shaped arm spines (Table 1, see also remarks for A. spinulosum sp. nov.).