Aquilonastra burtonii ( Gray, 1840 )

O, P. Mark, 2006, A systematic revision of the asterinid genus Aquilonastra O Loughlin, 2004 (Echinodermata: Asteroidea), Memoirs of Museum Victoria 63 (2), pp. 257-287 : 268-269

Aquilonastra burtonii ( Gray, 1840)

Figures 1, 2c–d, 5a, 7c–d

Asterina burtonii Gray, 1840: 289 .— Gray, 1866: 16.— Gray, 1872: 118.—H.L. Clark, 1923: 283 (status of species; possibly part).— Smith, 1927a: 641–645 (part).—A.M. Clark, 1952: 207 (possibly part; fissiparous; possibly A. yairi sp. nov. below).— Tortonese, 1960: 20–21 (probably part).

Asterina burtoni .— Tortonese, 1966: 3, fig. 1.—A.M. Clark, 1967a: 146, tbl. 1 (part; Red Sea material).— James and Pearse, 1969: 84–85 (part).—A.M. Clark and Rowe, 1971: 38 (part), 68, fig. 17a.— Tortonese, 1977: 281–282.— Price, 1983: 47–48, fig. 14 (part). — Archituv and Sher, 1991: 670.— Mladenov and Achituv, 1999: 152 (part). — Karako et al., 2002: 139–144 (part, El Fauz Red Sea population).

Asteriscus wega Perrier, 1869: 102 .

Asterina wega .— Perrier, 1875: 318.— Achituv, 1969: 329–341 (part, “pluriradiate” form).— Achituv, 1973a: 333–336 (part, Akhziz lagoon and Haifa populations).

Asterinides burtoni .— Verrill, 1913: 482.

Asterina gibbosa .— Tortonese, 1957: 190 (non Asterina gibbosa Pennant, 1777 ; see Tortonese 1966).

Aquilonastra burtoni .— OʼLoughlin and Waters, 2004: 11, 13 (part), 14.

Material examined. Lectotype (judged to be Grayʼs type by G.A. Smith, 1927a). Red Sea, NHM [18]40.3.23.54 (dry).

Asteriscus wega Val. , Red Sea, M. Botta, 1837, MNHN EcAs2713 (1) (labelled “ type ”; see Remarks; not A. burtonii ).

Red Sea, coll. Michelin, 1868, EcAs 1566 (6); Ras Muhammad, 8 Aug 1968, HUJ SLR1917 (5); Gulf of Suez , Et Tur, 20 Sep 1967, HUJ SLR845 (2); 20 Sep 1967, TAU NS2090 (1, fissiparous form); 24 Dec 1965, TM H1815 (2); Île Abulat, Calypso, EcAs 11842 (1); La Sicherie, EcAs11841 (1); S Sinai, El Fauz, Nov 2003, NMV F109383 (4); Gulf of Aqaba, near Dahab, 4 Nov 1981, TAU NS24408 (2, fissiparous forms); Sep 1976, TAU NS24501 (1); 18 Dec 1967, HUJ SLR1127 (1); 19 Feb 1968, SLR1341 (2) .

Oman, Masirah I., Bar al Hikman peninsula, coral rubble , 3–4 m, 7 Nov 1999, UF 1126 (2) ; 0–1 m, 7 Nov 1999, UF 3280 (1) ; 3–4 m, 23 Jan 2005, UF 4240 (1) ; UF 4239 (2) ; 1–8 m, 18–24 Jan 2005, UF 4237 (1).

Zanzibar, Prison I., seagrass bed, 6 Aug 1995, NHM 2004.2831 (1).

Diagnosis. Fissiparous Aquilonastra species; rays up to 8, frequently 7, form frequently asymmetrical post-fissiparity; form of larger specimens sometimes symmetrical with 5 equal rays; most interradii with inconspicuous madreporite; rays narrow basally, tapering, narrow rounded distally, digitiform; up to R = 18 mm; at R = 12 mm, r = 5 mm; gonopores not seen.

At R = 12 mm, lacking carinal plates; numerous secondary plates, intergrade with primary plates, frequently large irregular proximal abactinal plates; abactinal plates arched over papulae, rarely notched; spinelets small, variable in form, conical to columnar to digitiform, distally spinous, some splay-pointed, spread sparsely over plate surface, rarely up to about 15 spinelets on proximal plates, up to about 7 on mid-interradial plates; superomarginal plates each with up to about 6 spinelets, inferomarginal plates each with up to about 12 larger spinelets.

Spines per actinal plate up to: oral 6, suboral 3 frequently 2, furrow6,subambulacral4,actinalinterradial1–4(predominantly 3); interradial spines conical, sacciform.

Colour (live). “Greenish gray colour on the aboral side; a large and irregular, purplish brown blotch is on the centre, and is surrounded by red spots on the basal parts of the arms; the latter are usually darker (greenish) near their extremity, where a pale median line is to be observed” ( Tortonese, 1966; Haifa specimens; the red spots are presumed here to be the madreporites); “variegated yellowish, brown and red” ( Tortonese, 1977; Aqaba specimen); majority of 14 colour morphotypes from Elat were “mottled brown and orange” (pers. comm. Y. Achituv); Akhziz specimens were predominantly “mottled brown and orange” (pers. comm. Y. Achituv); “pale grey, mottled red and brown” (label with Zanzibar specimen); mottled browns, off-white (photos by G. Paulay).

Distribution. Eastern Mediterranean, Akhziz lagoon and Haifa populations; Red Sea, Gulf of Suez, Gulf of Aqaba; Arabian Sea, Oman; Arabian Gulf; NW Indian Ocean, Zanzibar; 0– 8 m.

Remarks. Smith (1927a) discussed in detail the historical confusion surrounding Grayʼs Asterina burtonii , and gave a full synonymy. Grayʼs type was reported lost, but Smith asserted that he had found two of Grayʼs type specimens of Asterina burtonii . We follow Smith (1927a), and accept that the larger of these two specimens ( NHM [18]40.3.23.54) is the type for Asterina burtonii . This lectotype for Asterina burtonii has five equal rays, but five small madreporites (R = 11 mm). We judge that the smaller of these two types ( NHM [18]40.3.23.55) is conspecific with a second Red Sea fissiparous species Aquilonastra yairi sp. nov. (below).

A Paris Museum specimen of Asteriscus wega Val. ( MNHN EcAs2713) labelled “type” was collected from the Red Sea by M. Botta in 1837. The Valenciennes manuscript name was not published, and this specimen has no type status. The name Asteriscus wega was published by Perrier who described (1869, 1875) 13 fissiparous specimens (syntype series) collected from the Red Sea by M. Botta in 1858. These fissiparous specimens, up to R = 15 mm (Perrier reported a diameter of 2–3 centimetres), are not conspecific with the Valenciennes non-fissiparous “type” specimen that has been examined here and has six equal rays and one conspicuous madreporite. It is referred below to Aquilonastra marshae sp. nov. Based on Perrierʼs 1869 and 1875 descriptions, Asteriscus wega Perrier, 1869 is judged to be conspecific with Asterina burtonii Gray, 1840 , of which it becomes a junior synonym. This decision supports the opinion of a synonymy by A.M. Clark (1952, 1967b) and A.M. Clark and Rowe (1971).

Achituv (1973a) studied large numbers of four eastern Mediterranen populations of small fissiparous asterinids from Acre, Akhziz pool, Akhziz lagoon and Haifa. For the first two populations maximum R = 8 mm; for the latter two populations maximum R = 17 mm. These results are closely consistent with data for the two fissiparous species from the Red Sea, A. yairi sp. nov. with R up to 7 mm (below) and A. burtonii with R up to 18 mm. The invasion of the Mediterranean by both Red Sea fissiparous species is judged to be the best explanation for this data.

Mladenov and Achituv (1999, abstract) reported genetic studies of four populations of Asterina burtoni :

1. non-fissiparous Red Sea population from Elat

2. sympatric fissiparous Red Sea population from Elat

3. two allopatric fissiparous Mediterranean populations

They observed a high genetic difference between the fissiparous and non-fissiparous Elat populations, but not as high as between some fissiparous populations. On the assumption that the fissiparous populations were the same species, they concluded that there were not separate species in the four populations. We judge that there are two species represented by the fissiparous populations, and that both species occur in the eastern Mediterranean and one of them at Elat. This would explain the high genetic differences observed by Maldenov and Achituv (1999). To us, the Mladenov and Archituv (1999) evidence supports a conclusion of three species. This conclusion is congruent with morphological differences.

Karako et al. (2002) reported similar genetic studies and results for four fissiparous populations from Akhziv, Shikmona, and Mikhmoret on the coast of Israel, and El Fauz at the mouth of the Gulf of Aqaba, and a non-fissiparous population at Elat at the northern end of the Gulf of Aqaba. “Pentaradiate”, rather than having a large conspicuous madreporite, was used to determine non-fissiparous specimens and can be misleading as the larger fissiparous specimens frequently have five equal rays but continue to have more than one inconspicuous madreporite. We judge, as above, that the Karako et al. results support an hypothesis of two fissiparous species and one non-fissiparous species. The three Mediterranean populations appear to us to be Aquilonastra yairi sp. nov. (below), and the El Fauz population A. burtonii . We refer the non-fissiparous species at Elat to Aquilonastra marshae sp. nov. (below). Specimens from all locations in the Karako et al. study, except Shikmona, were examined by us, and provide morphological support for the systematic decision that there are three separate species.

Tortonese (1936, 1966) first recorded A. burtonii in the Mediterrnean from Massawa (as A. wega ) in 1936. Mortensen (1926) reported a fissiparous specimen from the Gulf of Suez as Asterina burtonii , but gave insufficient detail to judge here whether the specimen was A. burtonii or A. yairi sp. nov. In OʼLoughlin and Waters (2004), material TM H1815 was referred to A. burtoni and that determination is confirmed here. A specimen TM H1814 was also assigned to A. burtoni , but is redetermined in this work as Aquilonastra marshae sp. nov. (below). There is no evidence in this study of a second smaller fissiparous species ( Aquilonastra yairi sp. nov. below) in the Gulf of Aqaba.

Soliman (1999) reported studies of two asteroid populations in the Arabian Gulf, understanding them to be both Asterina burtoni . There is no indication in the report that either population had fissiparous individuals, and we assume that Soliman studied non-fissiparous populations that were thus not A. burtonii . In this review three other asterinid species occur in the region: A. samyni sp. nov. (below, Oman) reaches R = 27 mm; A. watersi sp. nov. (below, Oman) reaches R = 19 mm; A. iranica ( Mortensen, 1940, Arabian Gulf) reaches R = 35 mm. One Soliman (1999) population was up to R = 26 mm in size, and we hypothesize that it was A. samyni . The other was up to R = 16 mm, and we hypothesize that it was A. watersi . Soliman (1995) also reported an asterinid population study in the Arabian Gulf at Qatar. The largest individual was R = 26 mm. Again, we hypothesize that the population was A. samyni .

A.M. Clark (1974) and A.M. Clark and Courtman-Stock (1976) reported Asterina burtoni for SE Africa, and referred to both single madreporite pentamerous and fissiparous specimens from Mozambique. A. burtonii is reported here from Zanzibar, and possibly occurs off Mozambique. H.L. Clark (1923) reported Asterina burtonii in the fauna of South Africa, but referred only to a specimen from Mozambique. Non-fissiparous specimens are not A. burtonii . Jangoux (1984), and Jangoux and Aziz (1984, 1988) reported Asterina burtoni for New Caledonia, La Réunion, Seychelles, Mineures and Maldives. We found no evidence to confirm A. burtonii in any of these localities. Following many authors, Walenkamp (1990) listed A. cepheus Müller and Troschel, 1842 , A. wega Perrier, 1869 , A. cephea var iranica Mortensen, 1940 and? A. anomala H.L. Clark, 1921 as junior synonyms of A. burtonii Gray, 1840 . We consider only A. wega to be a junior synonym. Walenkampʼs (1990) material is referred to A. richmondi sp. nov. (see below).

Perrier (1875), H.L. Clark (1923), Mortensen (1926), Smith (1927), A.M. Clark (1952) and Tortonese (1960) retained the original spelling of Gray ( burtonii ). Recent authors have used A. burtoni . Walenkamp (1990) argued for a restoration of the orignial spelling. We agree.

The characters distinguishing A. burtonii from A. yairi sp. nov. are detailed in the Remarks for A. yairi below. The mottled live colours for A. burtonii are red, orange, yellow, brown, grey, off-white.