Sea-Stars (Echinodermata: Asteroidea) from "Eltanin" Cruise 26, with a Review of the New Zealand Asteroid Fauna
Family Brisingidae Sars, 1875 — Brisinga Asbjornsen, 1856
Family Brisingidae Sars, 1875
Brisinga Asbjornsen, 1856
Brisinga tasmani n. sp. (Fig. 2, a-f; fig. 3, a-e; pl. 3, e, f).
One entire disc and fragments of about 12 arms, Sta. 1818; Sta. 1844 (1 arm).
Diameter of disc 50–43 mm., length of longest unbroken arm approx. 303 mm.; length of genital inflation approx. 105 mm.
Arms 15, long, sturdy, tapering distal to genital inflation.
Disc oval with gently rounded margin. Abactinal plates (fig. 2, a, b) small, oval, very tumid, generally isolated but contiguous at disc centre, near margins and at arm bases. Each plate bears from 2–7, exceptionally 8, short, tapering, hyaline spinelets; these are often finely toothed in last quarter, terminating in 2 or 3 distinct points. Crossed pedicellariae small, scattered, indistinct, squat, jaw tips toothed, distinctive teeth medially also. Abactinal membrane thin.
Madreporite (fig. 2, a) at disc edge, interradial, damaged, irregular, tumid, finely and deeply dissected; on disc side bordered by 3 or 4 very tumid, contiguous abactinal plates with short spines and crossed pedicellariae; on outer edge broad, more or less oval, flattened, slightly depressed, membrane covered area surrounded by heavily calcified region devoid of spines.
Anus (fig. 2, b) present as irregular opening on disc centre; adjacent plates more or less contiguous, forming circle.
Papulae absent from disc centre; possibly present on disc edge as very shallow indistinct pits occurring sporadically at arm bases.
Arms deciduous, breaking either at junction of first and second adambulacral plates, or in case of 4 arms, at junction of fifth or seventh adambulacral plate. Genital inflation occupies between 1/3 and ¼ total arm length.
From 20–27 more or less complete costae along arm, costae incomplete distally, absent near arm tip. Proximally, costae (fig. 2, c) salient, band-like, not sinuous, composed of small, oblong, overlapping plates, each plate with generally one or two (exceptionally as many as 5) small, conical, blunt or sharp-tipped, ridged spines which may be united basally by a thin membranous web. Crossed pedicellariae present on costal plates (fig. 2, c), also in distinct "felted" bands (fig. 2, c) between proximal costae and for some distance along arm; these bands most distinct laterally, often totally lacking abactinally. In crossed pedicellariae (fig. 3, a-d) median teeth small; blades distinctly sickle-shaped, hollow, terminating in number of teeth. Lateral plates adjacent to every second adambulacral tumid, enlarged, each with single, long, tapering 8–13 mm. spine; lateral spines increase in length distally, crossed pedicellariae similar to those described for abactinal surface present on both plates and spines. Intercostally, no scattered plates, although occasionally an isolated portion of a costa may be present. Gonads well developed, serially arranged along genital inflation, opening between lateral plates.
Adambulacral plates (fig. 2, d, e, f) band-like, with distinct aboral tongue projecting into furrow; plates separated by muscular intervals. Armature varies— page 26generally one slender, pointed, aboral furrow spine on tongue of plate which projects at right angles across furrow, almost meeting spine from opposite plate; one sturdy, tapering, ridged subambulacral spine almost central on plate with small, pointed subambulacral spine just below and adoral to it. In addition, occasionally a second, much shorter furrow spine (fig. 2, e) may be present immediately above first spine; in one or 2 cases a very small pointed furrow spine is present on adoral edge of plate and occasionally, proximally, 3 subambulacral spines form vertical row, that nearest furrow being smallest; distally there may be only one subambulacral spine. All spines, especially furrow spines, with numerous small crossed pedicellariae similar to those already described for abactinal surface.
Tube feet biserial with distinct sucking discs, in "pockets" formed by horizontal projecting adambulacral furrow spines; ampullae single.
Oral plates short, with 2 furrow spines, most proximal or actinostomial spine projecting horizontally across furrow, almost meeting spine from opposing plate; distal spine generally also projects horizontally across furrow; single suboral spine long, slender, ridged, tapering to sharp tip; all spines clothed along length with small crossed pedicellariae similar to those described above. Two most proximal adambulacral plates joined laterally, forming distinct carina; lateral plates corresponding to third adambulacral plates also joined, this carina being obvious from abactinal surface.
Fisher (1919, p. 501) uses the presence or absence of papulae on the disc and at the arm bases to distinguish between Brisingenes Fisher and Brisinga Asbjornsen. In the holotype of Brisingenes mimica Fisher (U.S.N.M. No. 37021), examined by the author, the papulae, both in the wet and dry states, are very conspicuous, occurring on the rounded margin on the disc at the arm bases. In the present specimen, although small and sporadic pits are present on the disc which could possibly be mistaken for papulae, by comparison with Brisingenes mimica, they are unimportant. Examination of the holotype and paratype of Brisingenes delli Fell (Dominion Museum) from the Bay of Plenty, New Zealand fails to show these very distinct marginal papulae and suggests that this species should be included in Brisinga. The author also had the opportunity of examining a specimen of Brisinga trachydisca Fisher (N.S.N.M. No. 40315) in which there are rather conspicuous papulae on the disc suggesting that this specimen should more properly be included in Brisingenes. Perhaps the presence or absence of these papulae should not be regarded as being of generic significance as it can be argued that indistinct papulae occur in places in both B. delli and B. tasmani; more material is necessary for comparison.
At least 7 species of Brisinga are known, all from the Northern Hemisphere. B. tasmani resembles both B. andamanica Wood—Mason and Alcock and B. gunni Wood—Mason and Alcock (both Indian Ocean) in having 15 rays but it differs from the former in having fewer costae, well developed genital inflations and in differences in the oral armature, while from the latter it can be distinguished by its stout, well developed arms, conspicuous and continuously salient costae and differences in the adambulacral plates. From B. trachydisca Fisher from the Philippines, it can be distinguished by having 15 rays (as opposed to 12 or 13), in having fewer costae and conspicuous intercostal bands of crossed pedicellariae, the pedicellariae being markedly smaller than those of B. trachydisca, and there are also differences in the adambulacral armature.
Abactinally, disc centre orange, edges white with orange patches at arm bases, arms orange-red, costae lighter, gonads showing through yellow-white. Actinally, actinostomial membrane dark red-brown, blue-grey at edges, lube feet pinkish-brown, page 27adambulacrals white to pale orange; distinct white areas between arms.
Known only from "Eltanin" Sta. 1818, 40° 15′–40° 17′ S., 168° 16′–168° 18′ E., west of Cape Farewell, New Zealand.
40° 15′–40° 17′ S., 168° 16′–168° 18′ E., west of Cape Farewell, New Zealand.
Location of Type:
United States National Museum.
Brisingid arms (Fig. 3, f, g; Pl. 3, g, h).
Fragments of about 23 arms, Sta. 1818.
Length of longest intact arm approx. 185 mm.; length of genital inflation 30–45 mm.; breadth of genital inflation, 5–8 mm.
Genital inflation small, commencing short distance from disc; costae (fig. f) 10–15 very conspicuous, salient, composed of contiguous rectangular plates, each with generally one (occasionally proximally 2 or 3) small, sharp-tipped spines; most proximal costae often incomplete. Gonads 2 in number, with branches extending along arms on either side of ambulacral plates; opening at beginning of genital inflation; gonads (fig. f) visible through abactinal membrane. Distal to genital inflation costae very indistinct, generally only 2 lateral plates and spines remaining. Membranous intercostal areas devoid of spines or plates although indistinct and incomplete bands of small crossed pedicellariae may be present, especially proximally; similar pedicellariae may also be present on costal spines. Lateral costal spines large, distinct, slender, tapering; proximally costae occur opposite every second adambulacral plate. On one arm, possibly result of injury, costae sinuous, fragmentary, individual plates tumid, crowded, each with one or 2 small sharp-tipped spines.
Adambulacral plates (fig. 3, g) rectangular, separated by distinct muscular intervals, each plate with short aboral tongue extending into furrow and a similar but less conspicuous adoral tongue projecting abactinally; in places this appears to form a separate hemispherical plate. Generally, one short, sharp-tipped adoral furrow spine, situated short distance from lateral edge of plate projecting across furrow; single aboral subambulacral spine-sturdy, hyaline, sharp-tipped; small crossed pedicellariae, similar to those already described, present both on furrow, and less conspicuously, on subambulacral spines. Occasionally, a second furrow spine may be present adjacent to first, and on several arms, proximally, there is a small, slender aboral furrow spine situated on distal extension of plate.
Tube feet biserial with small distinct sucking discs.
The presence of only 2 gonads in a ray, one on either side, combined with the delicate nature of the subambulacral spines suggests that these arms, according to Fisher's (1919, p. 501) key, belong either in Astrostephane Fisher or in Brisingella Fisher. It is difficult to go further than this as there is no disc. The 2 known species of Astrostephane are both from the Philippines-Indonesian region and the present arms differ considerably in both the adambulacral armature and in lacking conspicuous intercostal bands of pedicellariae.
Fisher (1928, p. 13) recognises 8 species of Brisingella and believes that 4 species described by Sladen probably also belong here; a further species was added by page 28Djakonov (1950) from Soviet Waters. Of these 9 definite species 7 are known only from the Northern Hemisphere, B. tenella (Ludwig) has been collected from near the Galapagos Islands and B. monacantha H. L. Clark is from Peru. Of Sladen's 4 doubtful species, 2 are from the Southern Hemisphere. The present arms appear similar to B. fragilis (Fisher) from Hawaii, especially in the adambulacral armature but they have markedly fewer costae; they are also similar to B. exilis (Fisher) from Southern California both in the adambulacral armature and in the number of costae. They differ from B. monacantha H. L. Clark in possessing adambulacral furrow spines, and from B. membranacea (Sladen)—from between Marion and Crozet Islands—they differ in the position of the furrow spines and there are also differences in the costae.
Abactinally, pink along arm edges, costae very delicate pale pink, gut purple. Actinally, pale yellow-pink.
Known only from "Eltanin" Sta. 1818, 40° 15′–40° 17′ S., 168° 16′–168° 18′ E., west of Cape Farewell, New Zealand, and Sta. 1844, 46° 40′–46° 44′ S., 165° 18′ E., west of Stewart Island, New Zealand.
Location of Specimens:
United States National Museum.
Brisingid arms (Fig. 3, h, i).
Fragments of 5 arms from Sta. 1844.
Largest fragment approximately 100 mm.; breadth at genital inflation approximately 4 mm.
Costae (fig. h) conspicuous on genital inflation; distally inconspicuous, confined to lateral regions only. Costal plates tumid, rectangular, imbricating, or sometimes overlapping; each plate with generally one, but occasionally (proximally) as many as 3 spines. Lateral costal plates with larger spines; spines short, round-tipped, fluted. Primary costae generally present opposite every third adambulacral plate. Secondary incomplete costae present abactinally; plates small, rather flat, often with only one small spine. Between costae, surface (fig. h) paved with small, contiguous, rectangular, square or round plates which show a less regular arrangement laterally; plates porous, thin, without spines; distal to genital inflation, plates fewer, less regular in arrangement and size. Occasional small crossed pedicellariae present intercostally, possibly also present around costal spines.
Adambulacral plates (fig. i) separated by distinct muscular intervals; single furrow spine aboral, slender, tapering, pointed, projecting over furrow, covered with small crossed pedicellariae. Crossed pedicellariae very small with flaring shafts terminating in a head armed with numerous small teeth. Subambulacral spine conspicuous, short, fluted, occasionally a second smaller subambulacral spine may be present.
Tube feet biserial with distinct sucking discs, each more or less enclosed in "pocket" formed by projecting furrow spines.
The absence of distinct papulae and the presence of intercostal plates places these arms in the second part of Fisher's (1919, p. 501) key and seem to limit the page 29choice to either Stegnobrisinga Fisher or Astrolirus Fisher; however the absence of the disc and most proximal part of the arms makes differentiation between the 2 difficult.
These arms resemble Astrolirus panamensis (Ludwig)—from Central America and from the Cocos Islands in the Indian Ocean—in having widely-spaced costae, incomplete secondary costae, short, stumpy costal spines, and in details of the crossed pedicellariae; there are differences, however in the adambulacral armature. The arms differ from the 2 known species of Stepnobrisinga (from Indonesia and the Indian Ocean) in the arrangement of the costae and in the adambulacral armature. This would be the first record of either of these genera from south of the equator.
No colour notes were made.
Known only from "Eltanin" Sta. 1844, 46° 40′–46° 44′ S., 165° 18′ E., west of Stewart Island, New Zealand.
Location of Specimens:
United States National Museum.