Benthogenia cribellosa Fisher, 1911

Fau, Marine, 2024, Revision of the genus Benthogenia Fisher, 1911 (Asteroidea, Echinodermata), with description of a new species and ossicle anatomy, Zoosystema 46 (11), pp. 269-284 : 273-275

publication ID	https://doi.org/ 10.5252/zoosystema2024v46a11
publication LSID	lsid:zoobank.org:pub:D636D084-4345-42B5-8094-F00C82A74A77
DOI	https://doi.org/10.5281/zenodo.11198859
persistent identifier	https://treatment.plazi.org/id/77255E47-642D-FF98-1016-FC71A020F845
treatment provided by	Plazi
scientific name	Benthogenia cribellosa Fisher, 1911
status

Treatment

Benthogenia cribellosa Fisher, 1911 View in CoL

( Figs 1 View FIG ; 2A, C View FIG ; 3A, C, E View FIG ; 4A, C, E View FIG ; 5A, C View FIG )

Benthogenia cribellosa Fisher, 1911: 415-417 View in CoL ; 1919: 39-443, pl.1 fig. 1, 2 fig. 1, 8 fig. 2. — Madsen 1961: 81-82. — Clark & Downey 1992: 92. — Gale 2005: 393-395. — Blake & Mah 2014: 182- 188. — Mironov et al. 2016: 503-516.

TYPE LOCALITY. — Republic of the Philippines, Mindanao Island, Iligan Bay, Tabu Point, 8°16’45”N, 124°02’48”E.

TYPE MATERIAL. — Holotype. Republic of the Philippines • Mindanao Island, Iligan Bay, Tabu Point ; station 5513 ; 8°16’45”N, 124°02’48’’E; depth 924 m; 7.VIII.1909; United States Fish Commission; USNM 28655 About USNM . GoogleMaps

MATERIAL EXAMINED. — Republic of the Philippines • 1 individual; South East of Cagayan Island; station 5425 ; 9°37’45.1”N, 121°10’58.8”E; depth 905 m; 31.III.1909; United States Fish Commission; USNM 40412 About USNM GoogleMaps • 1 individual; South East of Cagayan Island; station 5425 ; 9°37’45.1”N, 121°10’58.8”E; depth 905 m; 31.III.1909; United States Fish Commission; USNM 40417 About USNM GoogleMaps • 1 individual; West of Luzon Island; station CP 107; 14°01’12.0”N, 120°16’48.0”E; depth 111-115 m; 2.VI.1985; Bouchet & Triclot leg.; MUSORSTOM 3, dry; MNHN-IE-2019-3848 GoogleMaps • 1 individual, Bohol Sea; station CP2389 ; 9°16’48.0”N, 123°22’48.0”E; depth 784-786 m; 30.V.2005; coll. PANGLAO 2005 Deep Sea Cruise, GenBank: OR802153 ; MNHN-IE-2007-1828 GoogleMaps .

DIAGNOSIS. — Emended from Fisher (1911). Sea star with pentagonal disc, arms tapering significantly, cribriform organs well developed, present between all the marginals as well as the dorsal part of the superomarginals, from the disc to the tip of the arms. Cribriform organs covering entirely the six most proximal superomarginals of each interbrachium (arm tip to arm tip). From half way of the arm to the tip, superomarginals abutted dorsally along midline. Superomarginals 30 to 34 per interbrachium in large individuals, inferomarginals 32 to 34 per interbrachium. Adambulacral ossicles with five to eight furrow spines, most often seven or eight, and numerous subambulacral smaller spines or spinelets (usually 10 to 15). Oral ossicles large, with nine to 12 furrow spines, the most proximal spine, enlarged (two or three times the width of other oral furrow spines), pointed toward the mouth. Abactinal paxillae large, bearing up to 35 spinelets.

DESCRIPTION

Description based on the specimens MNHN-IE-2019-3848 ( Fig. 1E, F View FIG ), MNHN-IE-2007-1828 ( Fig. 1C, D View FIG ), and the original description of the holotype USNM 28655 ( Fig.1A, B View FIG ) in Fisher (1911).

Body pentagonal (R/r between 1.9 and 2.6), arms tapering. Superomarginals form distinct border when viewed abactinally, interbrachium (from arm tip to arm tip) composed of 30 superomarginals and 34 inferomarginals (34 superomarginals in MNHN-IE-2007-1828), the 10 proximalmost superomarginals forming the disc, the remainder abutting abactinally on the arms. Abutted superomarginals variably aligned regularly or offset in a same individual depending on the arm. Superomarginal plates decreasing in size along the arms, with the largest plates being the one proximal to the superomarginals abutted dorsally along the arms.

Paxillae densely packed on the abactinal surface, the largest paxillae on the distal part of the disc directly above the ambulacral groove with 28 or 30 spinelets par paxillae, in some up to 35. Smaller paxillae at the center of the disc with 15 to 25 spinelets each and smallest paxillae next to the marginal edges with four to five spinelets.

Madreporite close to the edge of the disc, 1 to 2 mm away from closest superomarginals, largest diameter 4 mm in MNHN-IE-2019-3848 and 6.5 mm in MNHN-IE-2007-1828. Terminal ossicles oval, relatively large (4 mm in MNHN-IE-2019-3848; 5 mm in MNHN-IE-2007-1828), overlapping the two distalmost superomarginals on each side of the arms, each terminal resting over four superomarginals in total. Terminal ossicles bearing spines up to five or six small spines.

Cribriform organs well developed on the disc and on the arms ( Fig. 2A, B View FIG ), covering all or almost all the surface of the ten proximalmost superomarginals ( Figs 2A, B View FIG ; 3A, C View FIG ), forming one continuous surface. Cribriform organs never covering the entire surface of the inferomarginals ( Fig. 2A, B View FIG ), but rather three quarters in the 10 proximalmost inferomarginals, with a bare area left in the center of the ossicles ( Fig. 2B View FIG ). Cribriform organs less developed on the arms, present between the abutted superomarginals on the abactinal side of the arms up to the terminal ossicle, and reduced to two rows of spinelets per fasciolar band on the distal part of the arms. Superomarginals with small spines directed abactinally, one per ossicle ( Fig. 3E View FIG ), no spines observed on inferomarginals (except for the cribriform organs). Inferomarginals aligned with superomarginals on disc, but offset distally due to their sizes decreasing more drastically than the superomarginals ( Fig. 4E View FIG ).

Actinals are scale like, covered in small spines ( Fig. 4A, C View FIG ). Adambulacrals with five to seven furrow spines, mostly six to seven ( Fig. 4A, C View FIG ). Subambulacral spines organized around the edges of the adambulacrals mostly, a few additional ones at the center of the ossicles ( Fig. 4A View FIG ). Very few small subambulacral spines on proximal adambulacrals, less than 10 per ossicle, increasingly distally to up to 12/16 spines on mid-arm ossicles.

Oral ossicles big, with a single tooth-like-spine per ossicle directed into the mouth, and eight to nine spines bordering the ambulacral groove (furrow spines), same shape as the ambulacral spines, nine to 10 furrow spines in total ( Fig. 5A, C View FIG ). More than 20 furrow spines, aligned along the edges of the orals. Proximal spines the biggest.

REMARKS

Three specimens, included in USNM 40412 and USNM 40417, were described by Fisher (1919), with the latter specimen containing two individuals collected from gut contents of a goniopectinid, Prionaster gracilis Fisher, 1913 . Fisher (1919) provided a detailed description of the largest specimen USNM 40412, R = 12 mm, but expressed doubt on its taxonomic identification, stating its resemblance with the genus Hyphalaster Sladen, 1883 and especially Hyphalaster hyalinus Sladen, 1883 . Examination of both specimens confirms Fisher’s observations that the specimens are B. cribellosa but due to their small size, lack characters present only in adults. USNM 40412 shows juvenile cribriform organs between all its marginals (i.e., the cribriform organs do not cover the entire surface of the marginals unlike larger specimens), possessed thick and round marginals, and a relatively large terminal ossicle covering the arm tip. This terminal ossicle morphology is typical of juvenile asteroids. Specimen USNM 40417 was not as well-preserved and included only a fragment of the arm, which also included part of the oral frame. Fisher (1919) described this specimens as the smallest, measuring R = 5.5 mm.