Calliaster mammilifer Alcock 1893

Mah, Christopher L., 2018, New genera, species and occurrence records of Goniasteridae (Asteroidea; Echinodermata) from the Indian Ocean, Zootaxa 4539 (1), pp. 1-116 : 21-22

Calliaster mammilifer Alcock 1893

Figure 6 A–F

Alcock 1893: 172; James 1983: 89 (checklist); Clark 1993: 246 (checklist); Sastry 2005: 28 (checklist) (as C. mammillifer )

Diagnosis. Species diagnosed based on arched disk, strongly prominent, large bullet-shaped spines sitting on strongly convex disk and carinal plates. Abactinal plates smooth, bare. Marginal plates, especially superomarginal plates smooth, strongly convex, almost round with two to five plates abutted over mid radius for most of arm distance. Furrow spines three to six.

Comments. Specimens described herein represent the first occurrence of this species since its description by Alcock (1893). Other mentions listed in the synonymy are reiterated in summary checklists and contain no new data. This species is identified based on comparisons with Alcock’s (1893) original description in addition to the only known, extant syntype in the MNHN collections (IE-2014-162) and new Somalian material from the USNM collections. It is unknown if extant type material of this species exists elsewhere. The MNHN syntype also appears to be the subject of the diagram for this species in the original description and accompanying plates (Alcock 1893). New material of larger individuals from Somalia have also been discovered and these details have been incorporated into the description below.

The type specimen from the Andaman Sea ( Fig. 6C ) differs in significant respects from the newer material from the western Indian Ocean. The type displays only the two distalmost superomarginals abutted over the midline, a character which appears to vary widely. An individual from Somalia (USNM E53618 ), comparable in size to the type, shows one arm with two and a partial third abutted superomarginals but with the other four arms showing consistently three or four abutted superomarginals per arm. The Madagascar specimens show four distalmost superomarginals fully abutted on all five arms ( Fig. 6A ), which suggests this character varies across its geographic range. Similarly the Andaman Sea type shows one to three spines present on the superomarginals and inferomarginals, respectively. Specimens examined herein show primarily single spines on all marginal plates. Otherwise these individuals all show similar characteristic round marginal plates, arm shape, and abactinal spine arrangement. Because the type specimen is relatively small (R= 1.6 cm) a description of this species based on the larger, Madagascar specimens is outlined showing the differing characters.

Karuppaiyan and Raja (2007) described what they identified as Calliaster childreni from the Bay of Bengal. The specimen and description presented in their paper is vague and although the image is unclear, it is similar in appearance to Alcock’s type specimen of Calliaster mammilifer . Although the specimen presented in Karuppaiyan and Raja’s account does look similar to C. childreni , its similarities to this Indian Ocean species and lack of comparative discussion give cause to regard this record of the largely Pacific C. childreni in the Indian Ocean with some skepticism.

Occurrence. Andaman Sea, Somalian coast, Madagascar. 60–448 m

Description. Body stout, stellate in shape (R/r=2.7–3.2), arms elongate, interradial arcs curved. Disk strongly arched ( Fig. 6D ). Arms upturned.

Abactinal surface composed of abutted plates, most plates weakly convex to flat with bare, smooth surface. Primary circlet and carinal plates with primary spines; each with strongly convex, smooth round base with distinct bullet-shaped spine tip ( Fig. 6C, D ). On the larger individuals (R>5.0), approximately six to eight smaller bulletshaped spines present on the abactinal plates on side adjacent to the superomarginal contact, otherwise, no surficial accessories present on central plate surface. Smaller individuals (R<3.0 cm) with no convex plates). Plates round to polygonal with largest plates proximally and smallest, most irregular plates present distally adjacent to superomarginal contact. Carinal plates strongly convex with most proximal three to six, mostly three to five, plates (individuals at R= 2.5–3.3 cm, up to 5.2 cm) bearing blunt conical spines rising well above the flat plane on the abactinal surface. The smallest specimens, R= 1.3 cm and the type at R= 1.6 cm show only one or two spines on proximalmost carinal plates. Distalmost carinal plates spineless but strongly convex continuing up to point where abutting superomarginals discontinue abactinal plate series. Individual plates with coarse peripheral granules, five to 40, mostly 20–30, mostly quadrate to irregularly polygonal in shape. Peripheral granules relatively large, occupying <25% of total diameter of each plate. Madreporite strongly convex, flanked by three to five plates. Papulae present over radial regions. No pedicellariae observed.

Marginal plates 16 per interradius (arm tip to arm tip) between R= 2.6 to 3.3 cm to 19 per interradius at R= 5.2 cm (in USNM E51265 ) with superomarginals offset from inferomarginals resulting in zigzag contact between them. The smaller syntype (at R= 1.6 cm) shows 12 while the smallest specimen (R= 1.3 cm) shows 10 per interradius. Superomarginals wide, quadrate in outline, plate surfaces strongly convex forming a scalloped edge around the edge of the body ( Fig. 6A, C, D ). Superomarginals most elongate interradially becoming narrower and most sharply convex distally, adjacent to the terminus. Superomarginals abutted over midline for most of arm distance, variably two to five in the syntype (R= 1.6 cm) to three to five in the large, Somalian specimens (>5.0). These plates were abutted along their distance with the proximalmost plate partially abutted along a tangential side. Superomarginals with one or two prominent conical spines projecting at different angles on central two to four interradial plates ( Fig. 6A, D ). One set of interradial spines on proximal abactinal surface of superomarginals versus the second which forms part of a distinct lateral series of single spines along the complete superomarginal plate series extending from the interradius to the arm tip. Other than the prominent conical spines, the superomarginal and inferomarginals are completely smooth and devoid of surficial granules, other accessories. Inferomarginals with one to four spines, mostly two or three present on plates extending from interradius to distalmost arm tip. Spines tallest medially becoming shorter to the side of each central interradial inferomarginal spine. As with superomarginals, no surficial granules or other accessories on inferomarginal plates. Marginal plate peripheral granules identical to those around abactinal, actinal plates, quadrate to irregularly polygonal present around the periphery of each, approximately 60 total, with 20 along the abactinal/inferomarginal contacts, 10 along the sides. Terminal plate enlarged, the size of three adjacent superomarginal plates, bearing three spines, surface smooth. Pedicellariae not observed.

Actinal surface flat composed of two full series ( Fig. 6B ). Each plate rounded quadrate to irregularly polygonal in shape, surface convex, smooth and bare with no accessories other than either a single large, conical spine or tubercle present on nearly every plate. One or two irregularly shaped adjacent to inferomarginals. Actinal plates abutted, no fasciolar groove, each with coarse grained peripheral granules, 7 to 30 identical to those on other plates.

Furrow spines six in the largest individual (R>5.0) ( Fig. 6E, F ), with the smaller type specimens bearing three to five, mostly four with one shorter spine proximally. Spines with higher numbers present more distally. Smallest specimen (R=1.3) with mostly three furrow spines proximally becoming four distally. Spines, blunt, finger-like, round in cross-section. Adambulacral plates with two enlarged, thick blunt spines in transverse series adjacent to the furrow spines ( Fig. 6E, F ). These large transverse spies at least twice the thickness of each furrow spine, with the one closest to the furrow spine about three times the height. The more distalmost spine shorter. The small specimen (R=1.3) with only a single enlarged subambulacral spine per plate. Oral plate with five furrow spines and one enlarged, blunt spine, triangular in cross-section per half of each plate directed into mouth. Oral plate surface with an enlarged, blunt spine, round in cross-section on each side of the oral plate (thus, two total) comparable in thickness and height to the other subambulacral spines. Medial suture bordered by eight or nine small, irregular granules.

Material Examined. Syntype IE-2014-162 Andaman Sea , Indian Ocean 493.7– 448 m (270–245 fathoms). 1 wet specimen R=1.6 r=0.5. Vouchers. IE-2007-3978 . Madagascar. 25°28’S 46°59’E, 155 m. Coll . ATIMO VATAE, N/O Nosy Be II, CP 3543 . 2 wet specs. R=2.8 r=1.0; R=2.8 r=1.1 . IE-2007-3979 . Madagascar. 25°14’S 47°18’E, 318 m. Coll . ATIMO VATAE, N/O Nosy Be II, CP 3513 . 2 wet specs. R=3.3 r=1.2 R=2.6 r=0.7 . IE-2007-4023 . Madagascar, 25° 37' S, 46° 19' S, 46°18’E, 347– 355 m. Coll . ATIMO VATAE DW3563 . 1 spec. R=1.3 r=0.4 .

Somalia. USNM E51265 , off NE coast of Somalia 9°36’N 51°01’E. 78–82 m, Coll. R / V Anton Bruun cr. 9, st. 444, coll. 16 Dec 1964. 1 wet spec. R=5.2 r=1.6 . USNM E51273 , off NE coast of Somalia 9°33’N 50°59’E. 75 m. Coll. R / V Anton Bruun cruise 9, st. 442. 1 wet spec. R=2.1 r=1.1 . USNM E51282 , SW of Ras Binnah 9°41’N 51°03’E, 60– 70 m. Coll. R / V Coll. R /V Anton Bruun cruise 9, st. 445. 1 wet spec. R=3.4 r=1.1 . USNM E52031 , off NE coast of Somalia and south of Socotra Island 11°24’N 51°35’E. 75–175m, Coll. R / V Coll. R /V Anton Bruun cruise 9, st. 463. 1 wet spec. R=1.4 r=0.5 . USNM E53618 , off NE coast of Somalia. 11°24’N 51°35’E, 75–175m Coll. R/ V Anton Bruun cruise 9, st. 9–463. 17 Dec 1964. 3 dry specs. R=1.8 r=0.6; R=1.6 r=0.6; R=1.9 r=0.75

Figures

FIGURE 6. Calliaster mammilifer A., B. Abactinal and actinal of IE-2007-3979. R=3.3, r=1.2 cm. Scale bar=1.0 cm. C. Abactinal surface of extant Alcock syntype (IE-2014-162). R=1.6, r=0.5 cm. D. to F. USNM E51265, R=5.2, r=1.6 cm, from Somalia, Abactinal, Furrow and Actinal surfaces respectively. Scale bar=1.0 cm for D, 0.1 cm for E, F.