Bathydorus spinosus Schulze, 1886

Bathydorus spinosus Schulze, 1886 View in CoL

Figs 11 View Fig , 12 View Fig ; Suppl. Tab. 10.

SYNONYMY. Bathydorus spinosus Schulze, 1886: 50 ; 1887: 153 and a number of followed publications. B. levis spinosus Wilson, 1904: 51 ; Ijima, 1927: 367; Koltun, 1967: 88; B. levis neospinosus ssp.n. (this publication, see the corresponding references).

MATERIAL. IORAS 5 /2/3809: RV ‘ Akademik M.A. Lavrentyev’ – 75, ROV ‘ Comanche’, sta. 9, spec. 3-3, 55.4253° N 167.2754° E, depth 783 m. GoogleMaps MIMB lv-82-7 sp1: RV ‘ Akademik M.A. Lavrentyev’ – 82, sta. 7, ROV ‘ Comanche’, 55.3689° N 167.2659° E, depth 984 m. GoogleMaps MIMB lv-82-7 sp2. RV ‘ Akademik M.A. Lavrentyev’ – 82, sta. 7, ROV ‘ Comanche’, 55.3688° N 167.2662° E, depth 981 m. GoogleMaps

DESCRIPTION. BODY. The specimen IORAS 5/2/3809 is 60 mm high and 30 mm in maximal diameter, at base about 15 mm in diameter, the walls are 1 mm thick. Other specimens are presented by fragments of the wall of corresponding thickness.

SPICULES. MEGASCLERES.Dermal and atrial spicules in the newly found specimens include hexactins and pentactins. The pentactins dominate among dermalia whereas hexactins dominate among atrialia.

MICROSCLERES. Oxyoidal microscleres are subdivided into two groups with thin 8–10 secondary rays and with thick with 1–4 secondary rays. The former are spherical oxyhexasters which are generally smaller than the latter type, which include oxyhemihexasters, oxyhemistaurasters, oxydiasters, oxyhexactins and other abnormal spicules.

REMARKS. The measurements of the spicules of this specimen are given in the Suppl. Tab. 10. The shape of dermal and atrial spicules entirely corresponds to those described and figured by Koltun (1967) for the specimens of the N Pacific (including the Bering Sea). While oxyoidal microscleres are different, the newly found specimens have notable amounts of abnormal oxyoidal microscleres: oxyhemistaurasters and oxydiasters.

This species epithet ‘ spinosus ’ was used as a subspecies epithet for a new subspecies of B. laevis — B. levis spinosus ssp.n. by Wilson (1904), that was also followed by Koltun (1967) ( levis a mistake of laevis ). Wilson (1904) did not provide any information on the preoccupied name ‘ spinosus ’ used for B. spinosus by Schulze, 1886 (see also Schulze, 1887). It is unclear what Wilson intended to do: to describe a new taxon or to suggest the transfer of the species ‘ spinosus ’ described earlier (1886) into another species ‘ levis = laevis ’ (1895) as a subspecies. In the first case, his taxon requires a new name, in the second — appropriate synonymization. The curiosity of this case is complicated by the notable similarity between B.levis spinosus of Wilson and B. spinosus of Schulze. Thus the operation of synonymization appears to be correct. Thus, we suggest a new name B. levis neospinosus ssp.n. for B. levis spinosus of Wilson to avoid the homonymy and simultaneously we make it a lower synonym of B. spinosus Schulze.

DISTRIBUTION. Cosmopolitan (except the Arctic Ocean), at 783–4847 m depth.

aff. Bathydorus sp.

Fig. 13 View Fig .

MATERIAL. IORAS 5 /2/3838: RV ‘ Akademik M.A. Lavrentyev’ – 75, sta. 18, specimen 3–3, ROV ‘ Comanche’, 55.4382° N 167.2652° E, 1559 m GoogleMaps .

DESCRIPTION. BODY. The specimen is represented by a small fragment attached to a dead skeleton of Farrea .

SPICULES. MEGASCLERES. Hypodermal (and hypoatrial pentactins as well), rarely stauractins with conically pointed, rough outer ends. The tangential rays of these pentactins are 0.3–1.0 mm long, the ray directed inside the body is 0.5–1.0 mm long, these rays are 0.009 –0.034 mm in diameter. Choanosomal diactins 2.3–3.7/ 0.008 –0.014 mm have stout shafts or with a widening in the middle with rounded, rough outer ends.

Dermalia and possibly atrialia are stauractins, rarely tauactins. They have slightly rough rays with conically pointed or rounded outer ends. The rays of these stauractins are 0.085 –0.344 mm in diameter (n=27, avg: 0.192 mm, std: 0.065 mm), the diameter of these rays is 0.004 –0.013 mm.

MICROSCLERES. Oxyoidal microscleres have very thin rays. They are usually oxyhexasters and oxyhemihexasters with 1–3 secondary rays, often curved or sometimes oxyhexactins. The diameter of oxyhexasters is 0.144 –0.237 mm (n=25, avg: 0.170 mm, std: 0.020 mm), the diameter of their primary rosette is 0.007 –0.015 mm (n=25, avg: 0.008 mm, std: 0.002 mm). The diameter of oxyhexactins is 0.148 – 0.215 mm (n=8, avg: 0.175 mm, std: 0.021 mm).

REMARKS. Among the species of Bathydorus only B. servatus Topsent, 1927 ( 1928) has similar oxyoidal microscleres with such thin rays. But dermal stauractins are much smaller as well as oxyoidal microscleres are also smaller in the newly found material, besides dermal diactins are absent (unlike B. servatus ). Based on a small fragment, description of a new species does not seem reasonable, moreover, the spicule content may be not complete and thus the generic identification is also not perfect. Spicules of other hexactinellids — Farrea and Periphragella were also found in investigated spicule preparations so the specimen is obviously contaminated by foreign spicules.