Parantipathes helicosticha Opresko, 1999

Lima, Manuela M., Cordeiro, Ralf T. S. & Perez, Carlos D., 2019, Black Corals (Anthozoa: Antipatharia) from the Southwestern Atlantic, Zootaxa 4692 (1), pp. 1-67 : 50-52

Parantipathes helicosticha Opresko, 1999

Fig. 27 , 28

Parantipathes helicosticha Opresko, 1999: 147–150 , fig 4–6; 2002: 437; Molodtsova & Pasternak, 2005: 169, 173, 174, 175, 177 and 178; Molodtsova, 2006: 146–147.

Type and type locality. SAM H–903 (holotype): Australia, 33º2’60”S, 125º20’60”E, 1011–1020 m . SAM H–904 (paratype): Australia, 33º45’0”S, 129º16’58.8”E, 999–1110 m . SAM H–901 (paratype): Tasmania, 44º14’45.6”S, 144º27’28.8”E, 1080–1130 m . SAM H–752 (paratype): Australia, 34º6’0”S, 131º19’58.8”E, 1124–1311 m .

Material examined. Rio Grande Rise , 30º33’17.28”S, 36º19’7.32”W; initial depth: 950 m; final depth: 1250 m. PROERG/ CPRM—EST: ERG 205 —Date: 08/02/2012 Amostr.: Dredge ( MNRJ 8595 , 1 specimen) . Rio Grande Rise , 31º10’0.12”S, 35º39’23.4”W; initial depth: 895 m; final depth: 855 m. PROERG/ CPRM—ERG 068— 17/06/2011 Dredge ( MNRJ 8600 , 1 specimen) . Rio Grande Rise , 31º9’0.36”S, 35º44’14.28”W; depth: 1087 m. PROERG/ CPRM—EST.: ERG 235 —Date 06/02/2012 Amostr.: Dredge ( MNRJ 8642 , 1 specimen, frozen) .

Diagnosis. “Corallum sparsely branched and pinnulate. Pinnules simple, arranged biserially in 6-8 (rarely 9 or 10) rows, and in semi-spiral groups of 3–4 (rarely 5) pinnules each. Pinnules extending at nearly right angles to the direction of stem or branch on which they occur. Spines simple, smooth, acute, inclined distally; 0.10–0.20 mm from center of base to apex. Spines arranged in axial rows, three or four of which are visible in lateral view; spaced 0.3–0.8 mm apart in each row; with 2–3.5 spines per millimeter. Polyps transversely elongated, 1.6–1.8 mm in diameter from proximal edge of proximal tentacles to distal edge of distal tentacles. Polyps arranged uniserially on upper side of pinnules, facing towards the distal end of the stem or branches. Interpolypar space about 0.6 mm, resulting in four polyps per centimeter” ( Opresko, 1999).

Description of Brazilian specimens. Corallum monopodial, unbranched, pinnulated. Soft tissue not preserved; skeleton dark brown ( Fig. 27a ). Specimens with total lengths of approximately 34 cm (MNRJ 8600), 58 cm (MNRJ 8595) and 38 cm (MNRJ 8642), only the specimen MNRJ 8600 has a basal disc. Stem thickness ranging from 1.25 mm to 2.5 mm. Pinnules in bottlebrush pattern, with simple pinnules arranged in five to eight rows, reaching up to 10 rows at the distal end in specimen MNRJ 8642. Pinnules grouped into 3 (in the proximal portion of the coral) to 5 pinnules (in distal portion) per semiespiral group, being more common the occurrence of groups of 4 pinnules in the median portion of the coral ( Fig. 27b ). Length of pinnules between 0.5 and 2.6 cm, most common between 1.2 and 2 cm, reaching greater length in the medial portion of the corallum. Pinnulation damaged in the most basal portions of the coral, in the three specimens analyzed. Basal diameter of the pinnules approximately 0.25 mm, but up to 0.40 mm in MNRJ 8600. Distal angle of the pinnules with respect to the stem approximately 80°. Distance between groups of pinnules 0.8 to 2.5 mm. Pinnules Spacing of pinnules within the same group usually around 0.30 mm, varying from 0.2 mm to 0.6 mm. Number of pinnules per centimeter between 24 and 33. Spines conical, smooth, inclined towards the distal end of the pinnule ( Fig. 27 c–d). Occasionally spines with a thin, curved apex toward the distal end of the pinnule. Spines on the pinnule arranged in 3 to 4 rows in lateral view, with a height between 0.06 and 0.13 mm, being more common near 0.1 mm on the polypar side of the medial and distal portion of the pinnule. Width of the base of spines varying from 0.08 mm to 0.2 mm. Distance between spines in the same row of approximately 0.6 mm, varying between 0.5 and 0.7 mm, with approximately 2 spines per millimeter in each row. Distance between rows of spines approximately 0.1 mm in the medial to distal portion of the pinnule. Polyps not visualized (lost tissue).

Remarks. The P. helicosticha specimens from the Rio Grande Rise present slightly larger pinnules than the holotype (up to 2.6 cm in the Rio Grande Rise, compared to 2 cm in those described in Opresko, 1999). However, the organization and density of the pinnules (up to 33 pinnules per cm in the present work, against 24–36 pinnules per cm in the holotype), and with a basal diameter of approximately 0.2 mm ( Molodtsova & Pasternak, 2005), as well as the general pattern of pinnulation, confirm the identification of the specimens for this taxon. The spines of the P. helicosticha samples described herein have a shape and density similar to the holotype spines, the size of the polypar spines being slightly smaller than that reported in Opresko, 1999 (0.08–0.13 mm in the present samples, against 0.1 to 0.2 mm in holotype). However, Opresko (1999) mentions that one of the paratypes (SAM H-752) has slightly smaller spines than the holotype. The spines of the P. helicosticha specimens detailed here, as expected for the species, are larger than the spines of species of Parantipathes already recorded for the Atlantic (0.06–0.09 mm for P. larix Brook, 1889 ; 0.03–0.09 in P. tetrasticha (Pourtalès, 1868) ; 0.03–0.05 in P. hirondelle Molodtsova, 2006 ). In addition, the studied material differs from P. larix and P. tetrasticha because it has smaller pinnules (0.5–2.6 cm compared to 6–12 cm in P. larix and 4 cm in P. tetrasticha ). The Rio Grande Rise samples are morphologically close to Parantipathes dodecasticha Opresko, 2015 , described for New Zealand. Said specimens differ primarily in number of pinnules per centimeter (24–33 in the present work, versus 35-40 in P. dodecasticha ), number of pinnules per semispiral group (3–5 in the present work, against 5–7 in P. dodecasticha ) and density of spines (2 spines per mm in the present work, against 4–5 spines per mm in P. dodecasticha ) ( Opresko, 2015).

Distribution. South Australia and South Tasmania ( Opresko, 1999), Valdivia Seamount, Walvis Ridge, Southeast Atlantic ( Molodtsova & Pasternak, 2005), and Southwestern Atlantic, Rio Grande Rise (this work) ( Fig. 28 ); from 575 m ( Molodtsova & Pasternak, 2005) to 1250 m (this work).

Figures

FIGURE 27. MNRJ 8600, MNRJ 8595: Parantipathes helicosticha Opresko, 1999. a 214 (MNRJ 8600)—Corallum morphology; b (MNRJ 8595)—Pinnulation pattern; c (MNRJ 215 8595)—organization of spines; d (MNRJ 8595)—Spines magnified.

FIGURE 28. Geographic distribution of Parantipathes helicosticha Opresko, 1999. Yellow circles: records extracted from the literature (Opresko, 1999; Molodtsova e Pasternak, 2005) and based on Ocean Biogeographic Information System (OBIS). Red circle: record made in the present work.