Paralomis makarovi Hall & Thatje, 2009, n. sp.

Paralomis makarovi n. sp.

(Figs 3, 4)

Material examined. Bering Sea: Bowers Bank, 54°30’N, 179°17’E, Albatross station 4772, 4.06. 1906, 629 m: male holotype, CL 23.8 mm; 3 male paratypes, CL 15–25 mm; 3 female paratypes. CL 12–23 mm (all USNM 1122582).

Etymology. This new species is named after V.V. Makarov, the author of an influential 1938 monograph on lithodid biogeography.

Description of the holotype. Carapace pear-shaped; rounded posteriorly, and longer than wide. Dorsal surface covered uniformly by conical spines, each with band of long setae half-way along length (Fig. 4 c) No spines dorsally or laterally notably longer than any other — no prominent spine at apex of gastric or branchial regions. Gastric region rounded and more prominent than branchial and cardiac regions, which are relatively sunken. Grooves only partially delimiting regions.

Median spine of rostrum strongly curved upward, and without secondary spinules or tubercles on ventral surface; one pair of dorsal spines, and one pair of spinules at their base. Rostrum not pedunculated, such that dorsal spines do not surpass cornea in dorsal view (Figs 3 f, 4f).

Spines on the lateral margins of carapace of similar size to those on dorsal surface; spines on frontal margin subequal, much shorter than eyestalk; 10–13 spines on each side of anterolateral margin; hepatic spines barely enlarged relative to others.

Ocular peduncles with long spine above cornea, and a few smaller spines along its length. Several setae above cornea (Fig. 3 c).

Second peduncular segment of antenna with moderately-sized spine on outer angle, and small spine on inner angle. Antennal acicle longer than ocular peduncle, consisting of one central spine, with 2 or 3 long outer spines and 2 or 3 smaller inner spines; all spines with several setae (Fig. 3 g).

Cheliped carpus with several spinules on medial face, without crest of large spines. Chelae with few spinules on dorsal border of palm, and several clusters of brush-like setae.

Merus of pereiopods 2–4 with 4 or 5 ill-defined rows of spines of various sizes; each row with 6 spines of a similar size to those on carapace. Dactylus of pereiopods 2–4 unarmed dorsally except for one at articulation and row of dark needle-like spines ventrally. Claw of dactylus recurved, with several clumps of setae.

Abdomen with marginal plates of segments 3–5 not separated from lateral plates, atypical of genus (Fig. 3 d); surface of plates without spines, but with low tubercles and several clusters of setae.

Variations. With the exception of the abdominal asymmetry typical of this family, no notable differences are observed between the males and the females. All individuals agree closely with the holotype.

Paralomis makarovi n. sp. (Figs 2, 3) Paralomis aspera Faxon Paralomis chilensis Andrade

Carapace outline Pear-shaped; rounded posteriorly. Pentagonal; as broad as long. Pear shaped; broader than long.

Longer than wide.

Antennal acicle One central spine, with 2 or 3 long At least 7 fully developed Acicle with many spines above

spinulation outer spines and 2 or 3 smaller inner spines, on inner and outer faces and below the plane. spines. All spines with several setae. of the acicle.

Remarks. Several species of Paralomis have the dorsal part of their carapace covered in dense, uniform spines. Under magnification, however, the structure of the spines is similar only to P. aspera and P. chilensis from the coast of South America, both of which have conical spines with a band of long setae half way along the length. Diagnostic differences between these species are set out in Table 2.

Paralomis makarovi has a geographic proximity to P. multispina and P. verrilli. A uniform coverage of spines on the carapace and on the pereiopods, with no dorsal spine more prominent than any other easily distinguishes P. m a k a ro v i from P. verrilli. Specimens of P. multispina of a similar size to the types of P. makarovi (Fig. 4 b) have been studied, and they are distinguished by the following features:

No enlarged spine on the apex of the gastric region of P. m a k a ro v i, whereas a large spine is found in this position on all P. multispina, and is especially prominent in smaller specimens.

Dorsal spines in P. m a k a ro v i conical, with a band of long setae half way down the spine. P. multispina has blunt spines with a single ring of short setae at the expanded apex (Figs 4 c, d).

P. multispina also has several long lateral spines on the carapace, whereas P. makarovi has none particularly more prominent than any other.

A pedunculation of the base of the rostrum is found in P. multispina, and not in P. m a k a ro v i.

It is quite likely that specimens belonging to P. m a k a ro v i have been found previously, but misidentified as P. multispina. The equivalent growth stages of these two species are, however, substantially different (Figs 4 a, b). Juvenile P. histrix, from Japan, also has a carapace covered with spines, but its spines are very long and are without setae. Paralomis histrix also has long spines on the abdomen, whereas the abdomen of P. m a k a ro v i lacks spines. Paralomis bouvieri Hansen, 1908, from the Northern Atlantic seems quite close to this species, except that spines have long setae eminating in a cluster from the apex in similar sized specimens.