Parantipathes laricides Van Pesch 1914

Parantipathes laricides Van Pesch, 1914

Fig. 25, 26

Parantipathes laricides Van Pesch, 1914: 104–105, figs 102-104; Opresko, 2002: 437; Molodtsova & Pasternak, 2005: 169– 179; Molodtsova, 2006: 146–147.

Type and type locality. Specimen not traced, Arafura Sea, between Australia and Papua New Guinea, 3º37’41.988”S, 131º26’24”E; 924 m.

Material examined. Rio Grande Rise, SA–MAR ECO /Marion Dufresni cruise ERG–Amostr.: ERG 017–22 Est: Dredge Date: 8–2011, (MNRJ 8589, 2 fragments). Rio Grande Rise, 33º26’16.8”S, 31º19’21.36”W; initial depth: 1876 m; final depth 1586 m. SA–MAR ECO /Marion Dufresni cruise L2 ERG—Est.: ERG 059L2 Am.: Dredge—Date 14/2011, (MNRJ 8598, 1 fragment).

Diagnosis. Corallum pinnulated, with pinnules grouped in semi verticils of up to 3 pinnules (sometimes one pinnule in a group missing) and a maximum of six rows. Pinnules usually between 1.25–1.75 cm long. Distance between groups of pinnules approximately 3.5 mm. Spines triangular and smooth, arranged in 3 rows on the pinnules and 4 rows on the stem in side view. Spine height up to 0.055 mm (polypar) and up to 0.01 (abpolypar) on opposite sides. Distance between adjacent spines in the same row of approximately 0.25 mm. Polyps about 1 mm between the sagittal and lateral tentacles, with approximately 2 mm in transverse extent, and 1.75 mm apart (adapted from Van Pesch, 1914 and Molodtsova & Pasternak, 2005).

Description of Brazilian specimens. Corallum monopodial or sparsely branched and pinnate. Skeleton with dark brown coloring. Stem thickness from 1.6 to 3 mm. Pinnulation in bottlebrush pattern (Fig. 25a). Pinnules simple, arranged in 6 to 7 rows, and in groups of 2 to 3 pinnules, rarely occurring in groups of 4. Length of the pinnules mainly between 1.0 to 2.5 cm, varying from 0.8 to 3.5 cm. Some pinnules, on one side of the coral, appearing to be the formation of new branches (Fig. 25b). Basal diameter of the pinnules between 0.30 and 0.80 mm, with thicker pinnules in the median region of the coral. Decreasing diameter in the base-apex direction of the pinnule. Distance between groups of pinnules on the same side from 1.00 to 2.25 mm. Distance between pinnules of the same group of approximately 0.5 mm. Number of pinnules per centimeter from 16 to 19. Spines small, smooth and triangular, with rounded apex, arranged in 4 to 5 rows in lateral view (Fig. 25 c–d). Size of the spines varying from 0.025 to 0.065 mm, being more common between 0.03 and 0.04 mm. Width of base of spines between 0.05 and 0.08 mm. Distance between spines of the same row of approximately 0.3 mm, varying between 0.3 and 0.4 mm, with 3 to 4 spines per millimeter. Polyps not visualized (lost tissue).

Remarks. The only specimen known of P. laricides is the type described by Van Pesch (1914), which represents a colony 7 cm long without a base (Molodtsova & Pasternak, 2005). The specimens described here differ from the type mainly by have longer pinnules (up to 1.75 cm in Van Pesch, 1914 against up to 3.5 cm in Rio Grande Rise specimens), and shows a lower density of pinnules than the type [up to 3 pinnules per group in the holotype (Molodtsova & Pasternak, 2005) against 2–3 pinnules per group in Rio Grande Rise specimens, rarely 4]. These differences may be due to the colonies studied here being larger and possibly more mature than the type. The MAR ECO specimens had pinnules with a higher basal diameter (up to 0.8 mm) than that reported for other species of the genus [larger basal diameter of 0.5 mm in P. tetrasticha (Pourtalès, 1869)]. This character was not described for the type of P. laricides, and analysis of the type material was not possible. MNRJ 8589 and MNRJ 8598 had spines in more rows than reported for the species in Molodtsova & Pasternak (2005) (3 to 4 rows in lateral view in P. laricides, against 4 to 5 in the samples studied), and slightly larger than the type (up to 0.05 mm in Van Pesch, 1914; up to 0.065 described here). No significant differences were observed between the size of the polypar and abpolypar spines in the material coming from the Rio Grande Rise. The taxonomic characteristics discussed here for species of the genus Parantipathes Brook, 1889 are summarized in Molodtsova & Pasternak (2005) and Molodtsova (2006). Pasternak (1977) in establishing the species Parantipathes wolffi comments that P. wolffi could be synonymous with P. laricides Van Pesch, 1914, since the type of the latter corresponded to a damaged fragment and not to a complete colony. Pasternak (1977) also notes that the types of both species were collected in the same biogeographic region (P. laricides in the Arafura Sea, between Australia and Papua New Guinea, and P. wolffi in the Malacca Strait, off the Malay Peninsula), and differ only by the number of pinnules per semi-verticils (mainly 3 in P. laricides, versus 2 in P. wolffi). The possible synonymy was also pointed out in Molodtsova & Pasternak (2005).

Distribution. IndoPacific, Arafura Sea (Van Pesch, 1914) and Southwestern Atlantic, Rio Grande Rise (this work) (Fig. 26); from 924 m (Van Pesch, 1914) to 1876 m (this work).