Disasterina Perrier, 1875

Saba, Masaki, Iwao, Kenji & Fujita, Toshihiko, 2012, A New Asterinid Sea Star, Disasterina akajimaensis (Echinodermata: Asteroidea) from the Ryukyu Islands, Japan, with Notes on the Genus Disasterina, Species Diversity 17 (1), pp. 21-28 : 21-24

Genus Disasterina Perrier, 1875

[New Japanese name: Numeri-itomaki-hitode-zoku]

( Table 1 ; Fig. 1)

Disasterina Perrier, 1875: 289 [reprinted in 1876: 209–210]; Livingstone 1933: 5–7; H. L. Clark 1946: 138; Spencer and Wright 1966: U69; A. M. Clark 1993: 218; Liao and A. M. Clark 1995: 131–132; Rowe and Gates 1995: 35; O’Loughlin and Waters 2004: 19–20 .

Habroporina H. L. Clark, 1921: 34 . Synonymized by A. A. Livingstone (1933).

Manasterina H. L. Clark, 1938: 157–158 ; H. L. Clark 1946: 139; A. M. Clark 1993: 220; Rowe and Gates 1995: 36. Synonymized by O’Loughlin and Waters (2004).

Type species: Disasterina abnormalis Perrier, 1875 (by monotypy).

Comparative material. D isasterina ceylanica Döderlein, 1888: 1 alcohol specimen, Naturhistorisches Museum Basel ( NMB) , réf. 2, probably one of the syntypes; Trincomali , Ceylon, collected by Paul Sarasin and Fritz Sarasin; R/r=20/ 8 mm . Disasterina odontacantha Liao, 1980: 1 dry specimen, NSMT E-4218 ; Ambon Island , Indonesia, 0–16 m deep; R/r=11/ 6 mm .

Remarks.O ’Loughlin and Waters (2004) included ve species in Disasterina : D. abnormalis (type species), D. odontacantha , D. ceylanica , D. longispina , and D. spinosa Koehler, 1910 . Disasterina odontacantha is clearly congeneric with D. abnormalis , sharing an uncalci ed interradial area just distal to each oral plate pair, a single spinelet per actinolateral plate, and a single spinelet per subambulacral plate ( Table 1 ). The other three species are quite di erent, and their generic attribution is doubtful.

Apparently without examining specimens, but relying only on Döderlein’s (1888) original description, Livingstone (1933) transferred Disasterina ceylanica to his new genus Tegulaster on the basis of having mid-radial abactinal plates forming a keel, but O’Loughlin and Waters (2004) reassigned the species to Disasterina . We have re-examined one specimen of D. ceylanica (Fig. 1), probably one of the syntypes ( Jangoux 1985: 21 called this specimen “ holotype ” without lectotype designation) although the measured body size (R/r=20/ 8 mm) does not exactly match that of any of the three syntypes (R/r=32/10.5, 25/10, 14/ 7 mm) mentioned in the original description ( Döderlein 1888: 825). We compared this specimen with the list of di erences between Disasterina and Tegulaster given by O’Loughlin and Waters (2004: 20), and some of its features suggest that this species should indeed be referred to Tegulaster . The body is not thin, but has a relatively thick disc and a mid-radial keel on the arms; the abactinal plates are fairly contiguous, with only small papular spaces, most of the abactinal plates being arranged longitudinally on the arms; the superomarginal plates are in distinct series; and the body is covered by a smooth integment. While the form and pattern of spinelets are similar in these two genera ( O’Loughlin and Waters 2004), in this specimen of D. ceylanica only some plates on the central disc and around the periphery of the madreporite have spinelets, the actinal plates each have one large spine, the adambulacral plates have four to ve webbed furrow spines and two subambulacral spines, and the oral plates have nine webbed furrow spines, the two or three innermost ones being larger than the rest, and two suboral spines.

Based on a single specimen, Disasterina longispina was originally described in the monotypic genus Manasterina by H. L. Clark (1938), distinguished in particular by its size, the openly meshed abactinal plates, the single spinelet per abactinal plate and long, slender spinelets near the arm tips, and the absence of uncalci ed interradial areas. Following their examination of three additional specimens from Western Australia, however, O’Loughlin and Waters (2004) recognized no generic value in such di erences and synonymized Manasterina with Disasterina . In light of several characteristics similar to those of D. ceylanica , in our view there remains a question as to whether Manasterina longispina should be referred to Disasterina or Tegulaster .

Disasterina spinosa was considered to be a valid species by Livingstone (1933), but not referable to Disasterina ; it has, however, been retained in Disasterina by O’Loughlin and Waters (2004). These latter authors noted that the long, sacciform spinelets on the abactinal plates are the most distinctive characteristic of this species, but also that this characteristic has no generic value. Several other characteristics of D. spinosa are similar to those of D. ceylanica , though suggesting that this species may also be better referred to Tegulaster than to Disasterina .

The descriptions of these three species were based on only one or a few specimens, and more material is required to clarify their generic status.

O’Loughlin and Waters (2004) removed D. leptacantha Livingstone, 1933 (see also O’Loughlin 2009) and D. praesignis Livingstone, 1933 (with its junior synonym D. spinulifera H. L. Clark, 1938 ) from Disasterina to Tegulaster . The generic status of D. ceylanica , D. longispina , and D. spinosa needs further consideration especially in relation to these species of Tegulaster . In addition to morphological evidence, molecular phylogenetic studies may be e ective in resolving the generic status of the species of Disasterina .

Another synonymized genus, Habroporina , was established by H. L. Clark (1921) monotypically for Habroporina pulchella H. L. Clark, 1921 . He did not mention the presence of interradial uncalci ed areas in this species, but his photographs (H. L. Clark, 1921: pl. 24 g. 3, pl. 26 g. 5) clearly show them. Livingstone (1933), nding no di erences between H. pulchella and Disasterina abnormalis , synonymized them.

Tables

Tableç1.C haracteristics of the species of Disasterina. N: number of specimens recorded. R, r: body size (R,r) in mm. R in parentheses is shown without r. R/r: R/r ratio. Body: L=low and at, H=high with median keel on rays. IUA: interradial uncalci ed area, P=present, A=absent. ABS: number of abactinal spinelets. SMS: number of superomarginal spinelets. IMS: number of inferomarginal spinelets. ALS: number of actinolateral spines. OS: number of oral spines. SOS: number of suboral spines. FS: number of furrow spines. SAS: number of subambulacral spines. Numbers in parentheses for ABS and IMS are observed for only several particular plates. Asterisks (*) indicate type locality.

Species	N	R, r (mm)	R/r	Body	IUA	ABS	SMS	IMS	ALS	OS	SOS	FS	SAS	Geographical distribution	References
D. abnormalis Perrier, 1875	25	R=19–30 r=8–15 (R<38)	2–2.5	L	P	0	0	1–5	1	4–6	1	2–5	1	New Caledonia *; Great Barrier Reef; Torres Strait; Indonesia; NW	Perrier (1875), H. L. Clark (1921), Livingstone (1933), Jangoux (1978, 1986), O’Loughlin and Waters (2004)
														Australia
D. ceylanica Döderlein, 1888	3	R=14–32 r=7–10.5	2–3.1	H	A	0	0	4–5	1	9	2	4–5	2	Ceylon *	Döderlein (1888), present study
D. longispina (H. L. Clark, 1938)	4	R=24 r=12	2.0	H	A	0–1 (2–5)	0	2–4	1	5	1	3–4	1	W Australia *	H. L. Clark (1938), O’Loughlin and Waters (2004)
D. odontacantha Liao, 1980	16	R=11–20 r=6–9 (R=9–25)	1.8–2.2	L	P	1–2	1	4–5 (3, 6)	1	3–4	0	3–4	1	Paracel [Xisha] Is. *; Indonesia; Fiji; Guam	Liao (1980), Liao and A. M. Clark (1995), Fujita and Marsh (2004), O’Loughlin and Waters (2004)
D. spinosa Koehler, 1910	1	R=14 r=5	2.8	H	A	1–3	3–4	1–2	2	7–8	3	5	3	Andaman Is. *	Koehler (1910)
D. akajimaensis sp. nov.	1	R=16.9 r=8.1	2.1	L	P	0 (2–5)	0	2–4	1	4–5	0	1–3	1	Ryukyu Is. *	present study