Capillaster squarrosus, Messing, 2003

Messing, Charles G., 2003, Three new species of Comasteridae (Echinodermata, Crinoidea) from the tropical western Pacific, Zoosystema 25 (1), pp. 149-162 : 154-158

Capillaster squarrosus n. sp.

( Fig. 2 )

HOLOTYPE. — Vanuatu. MUSORSTOM 8, stn DW1071, 15°37’S, 167°16’E, 180-191 m, 4.X.1994 ( MNHN EcCh 189).

PARATYPES. — Vanuatu. MUSORSTOM 8, stn DW1021, 17°43’S, 168°37’E, 124-130 m, 28.IX.1994 ( MNHN EcCh 188) ; stn DW1086, 15°37’S, 167°16’E, 182-215 m, 5.X.1994 ( MNHN EcCh 187) ; stn DW1071, 15°37’S, 167°16’E, 180- 191 m, 4.X.1994 ( MNHN EcCh 190) .

ETYMOLOGY. — From the Latin squarrosus meaning “rough with stiff scales” ( Brown 1956), a reference to the scaly roughened appearance in naked-eye view of arm ossicles from brr 6-10 to brr 20-25.

DISTRIBUTION. — Known only from Vanuatu in 130 to about 180 m (possibly 215 m). Two specimens identified as Capillaster multiradiatus (Linnaeus, 1758) by A. H. Clark (1931) from the Kei Islands, Indonesia, in 20-85 m, may represent this species (see below).

DIAGNOSIS. — A small species of Capillaster (ray length up to c. 100 mm) with up to 20 arms; cirri with up to 30 segments, 21.0 mm long; brachials brr 6-10 through brr 20-25 triangular, distinctly wider than those preceding, swollen and with strongly thickened spinose distal margins, so that the proximal half of the arm appears distinctly roughened, scaly and up to 1.5 times wider than the arm base in naked-eye view; pinnule combs present to about P 16-19.

DESCRIPTION

Centrodorsal discoidal, often with sloping sides, 4.0- 5.4 mm across; D/H 3.4-4.0. Polar area faintly depressed or convex; larger specimens with five faint interradial swellings radiating from around a shallow central depression.

Cirri XX-XXVIII, 23-30, up to 21.0 mm, in single or partly double crowded marginal row. Larger specimens have fewer cirri; c1 short; following cirrals increasing in length to c5; c4 with L/ W 0.8 -1.1; c5 longest, transitional, with oral margin slightly concave and with slightly raised dentate distal aboral margin, L/ W 1.3 -1.8. Following cirrals polished, becoming shorter, compressed, squarish by c9, shorter than wide thereafter with L/ W 0.8 -0.9. Cirrus slightly tapered distally; distal 2-3 cirrals preceding claw

A sometimes with L/ W 1.0. Raised, dentate aboral distal margin of c5-6 becoming strong curved midaboral spine flanked by one to three pairs of smaller spines by c7-9; flanking spines usually reduced to single pair on distal cirrals, but sometimes disappearing beyond about c20; strong midaboral spine becoming erect on distal cirrals. Opposing spine erect and sharp; penultimate cirral squarish, smaller than preceding cirrals, without flanking spines; claw longer than penultimate cirral. Distal margin of radials just visible beyond centrodorsal margin, more visible in interradial angles; distal margin concave, slightly concave in smaller specimens. Brachitaxes aborally convex, with or without weak midaboral synarthrial swellings. Ibr 1 short, oblong or shallow U-shaped in aboral view, united and sometimes slightly inflated laterally, with slightly diverging lateral margins; W/L 4.0-5.6 (MNHN EcCh 190 with lateral margins united only proximally and converging distolaterally; W/L 3.9). Ibr 2 (axil) almost triangular (lateral margins extremely short), apposed or separated laterally; W/L 1.8- 2.4. IIBr series chiefly 4(3+4); IIbr 1 short, oblong, united interiorly, sometimes with a few small midaboral spines; IIbr 2 cuneate or almost triangular, longer exteriorly, with a strongly thickened and finely spinose aboral distal margin, and with W/L 2.3-3.1. IIbr 3+4 pentagonal, the distal angle thickened and finely spinose; W/L 1.8-1.9. MNHN EcCh 188 bearing two IIBr2 on one ray, resembling IBr2 but smaller; MNHN EcCh 189 with 7 IIBr4(3+4) and 3 IIBr3(2+3).

Arms 12-20; ray length 85-102 mm. Some arms sometimes distinctly broader at the base than others. Distal aboral margins of brachials thickened and finely spinose. On arms arising from IBr series, br 1 and br 2 both longer exteriorly; br 1 united interiorly, with W/L 2.9-3.2; br 2 longer than br 1, with W/L 2.5; br 3+4 oblong, W/L 2.2- 2.5 and 2.1-2.5 mm across. On arms arising from IIBr series, br 1 oblong or cuneate, united interiorly, with W/L 1.4-1.9; br 2+3 oblong, with W/L 1.7-2.1 and 1.8-2.4 mm across. br 4 and br 5 usually oblong and no wider than br 2+3, sometimes slightly cuneate and wider; W/L 2.0-2.6. Following brachials cuneate, becoming distinctly wider, swollen and almost triangular with strongly thickened, spinose distal margins and distinctly darker articulations by brr 6-10; W/L 2.3-2.6. Widest brachials 1.2-1.3 times diameter of arm base, but up to 1.5 times when measured across the combined width of two successive brachials. Brachials gradually diminishing in width beyond about br 20, reduced to same diameter as arm base by about brr 25-28; the combination of swollen brachials and dark narrow articulations giving the proximal half of the arm a distinctly roughened, scaly appearance in naked-eye view. Following middle brachials smaller, narrower, less swollen, not as strongly cuneate, with weaker distal thickening; W/L 2.2-2.6. Distal brachials short, weakly cuneate; distal margins finely spinose but only slightly thickened; W/L 1.5-2.1. Brachials near arm tip almost oblong or squarish.

Syzygies on arms arising from IBr series at br 3+4, br 11+12 to br 14+15, and at intervals of 4-6 muscular articulations thereafter. On arms arising from IIBr series, syzygies at br 2+3, br 10+11 to br 20+21, and at intervals of 5-8 (rarely 9) thereafter. Some arms tend to have two longer intervals (7-9) following the second syzygy and shorter intervals (5- 6) thereafter.

P II of up to 33 segments, 14.2 mm, with nine tall triangular teeth. Proximal several pinnulars wider than long with expanded, spinose distal rims; middle segments with L/ W 1.8 -1.9, only slightly shorter than proximal pinnulars, but much narrower and centrally constricted, with distal spines disappearing by mid-pinnule and only a single strong, conical, lateral spine remaining on distal segments preceding comb. Several pinnulars just preceding comb shorter and wider, with L/ W 1.6. P 1 sometimes similar to P II, of up to 34 segments, 11 teeth, 11.8 mm long; sometimes slenderer and much shorter, with proximal pinnulars as long as wide by the fourth segment and middle segments with L/ W 2.0 -2.1. P 2 of up to 30 segments, 13 teeth, 6.6 mm. Following several pinnules similarly short but with more elongated middle segments. P 7 up to 22 segments, nine teeth, 6.1 mm; following pinnules gradually becoming longer. Combs present to about P 16-19.

Middle pinnules of up to 24 segments, nine A.H. Clark (1931) placed the type of C. borneteeth , 7.3 mm; proximal few pinnulars (some- ensis (Grube, 1875) as a synonym of C. multitimes excepting the short first) with expanded, radiatus rather than C. tenuicirrus despite its having spinose distal rims; middle pinnulars with cluster cirrals longer than broad from the fifth onward. of spines on side facing arm tip, L/ W 1.8; pinnu- Capillaster squarrosus n. sp. most closely resemlars preceding comb with two or three strong lat- bles C. multiradiatus but differs consistently as eral spines arranged in a transverse row. Distal follows. C. squarrosus n. sp. has a distinctive series pinnules slender, up to 22 segments, 7.4 mm; of swollen triangular proximal brachials ( Fig. 2F, G ) pinnulars beyond basal two longer than wide, whereas the same ossicles in C. multiradiatus are centrally constricted and with one or a few lateral short and resemble the following brachials spines, L/ W 2.4 -2.7. ( Fig.2A ). The cirri in C. squarrosus n. sp. consist Disk naked, anus central, mouth excentric. Anal of more cirrals at a shorter length than in C. multicone and surrounding interambulacral area with radiatus. Finally, pinnule combs occur as far as small, scattered papillae in one specimen. P 4-10 (rarely P 15) in C. multiradiatus and as far as P 16-19 in C. squarrosus n. sp. Two specimens DISCUSSION briefly described by A. H. Clark (1931: 188, Hoggett & Rowe (1986) include seven species in 189; probably in the Zoologisk Museum, Capillaster . C. macrobrachius (Hartlaub, 1890) Copenhagen , but Clark listed no catalogue numbears a small stellate centrodorsal lacking cirri, bers) as C. multiradiatus may represent C. squar- and C. asterias A. H. Clark, 1931 bears a few cirri rosus n. sp., although both were collected in composed of elongated segments that taper to a shallower water than the specimens described fine tip. The remaining species have more than above. One (Danish Kei Islands Expedition, 10 cirri with distal cirrals shorter than proximal stn 40, 25.IV.1922, 25 m, T. Mortensen coll.) cirrals. Of these, C. sentosus (Carpenter, 1888) has 19 “unusually stout” arms that “increase in and C. gracilicirrus A. H. Clark, 1912 bear more width to about the twentieth brachial, where they than 40 (often more than 60) arms, while the are twice as broad as at the base”; cirri of 29- remaining three ( C. mariae (A. H. Clark, 1907) , 30 segments, 22 mm long, and pinnule combs C. multiradiatus (Linnaeus, 1758) and present to near the arm tips, though “becoming C. tenuicirrus A. H. Clark, 1912 ) rarely have more and more reduced”. The other (stn 53, more than 30. C. mariae differs from C. multira- 8.V.1922, 85 m) has 15 arms (140 mm; longer diatus in having perfectly smooth brachitaxes than in C. squarrosus n. sp.), and cirri of 31- (division series) and a mottled disk lacking any 32 segments, 25-30 mm long. Its largest cirri are calcareous nodules. However, the distinctions similar to those of several C. sentosus examined, among several of these species remain unclear. but the latter have many more arms (33-80). A.H. Clark (1931) mentions five specimens ofLikewise, a specimen of C. sentosus with cirri C. multiradiatus (out of 214) with 40-43 arms similar to those of C. squarrosus n. sp. also has and seven specimens of C. sentosus (out of 32) many more arms (60). with fewer than 37 arms. Although cirri are typically ≤ 25 mm long with ≤ 25 segments in the former and greater than this in the latter, he also Genus Cenolia A. H. Clark, 1916 refers to individuals of C. multiradiatus with cirri of up to 27 segments or up to 30 mm long. No TYPE SPECIES. — Comatula trichoptera Müller, 1846 . other features are known to distinguish the two. DIAGNOSIS. — A genus of Comasteridae with IBr2 C. gracilicirrus differs from C. sentosus , and joined by synarthry; first brachial syzygy br 3+4 at on all C. tenuicirrus differs from C. multiradiatus , only of two ossicles occurring irregularly; P on br 1 2; pinnule arms; brachitaxes beyond IBr usually 4(3+4), any series in having distal cirrals slightly longer than broad combs usually present as far as P4, sometimes to P19, rather than broader than long. However, consisting of pairs of straight teeth of more or less equal size, each confluent with the pinnular margin; teeth of a pair sometimes joined to form a transverse bar; aboral surface of disk not heavily plated; mouth excentric (emended from Rowe et al. 1986).

REMARKS

Cenolia amezianeae n. sp., described below, differs from all species previously assigned to Cenolia in having combs present on pinnules distal to P 4. Instead, combs occur to between P 8 and P 19, although one or two more proximal pinnules sometimes lack one. It also differs in having usually rod-shaped calcareous nodules on the disk and proximal arm ambulacra, although tegminal deposits vary within the genus, and these may be similar to the small spines reported around the anal cone in C. tasmaniae (A. H. Clark, 1918) . C. amezianeae n. sp. shares with the other five members of the genus all other diagnostic features.

Figures

FIG. 2. — A, Capillaster multiradiatus (Linnaeus, 1758), brr9-11, 09°45’N, 118°42’E, 18 m, 17.IV.1995, Messing coll. (CRI-014); B-G, Capillaster squarrosus n. sp.; B, cirrus (MNHN EcCh 189); C, PII (MNHN EcCh 187); D, P2, same; E, P19 (MNHN EcCh 189); F, IBr2 and proximal part of one arm (MNHN EcCh 188); G, IIBr4(3+4) plus proximal part of normal arm (right) with br2+3, and abnormal arm base with br1+2 (left) (MNHN EcCh 189). Scale bars: A, C-E, 1 mm; B, F, G, 2 mm.