Trissopathes cf. tristicha ( Van Pesch, 1914 )

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 : 19-21

Trissopathes cf. tristicha ( Van Pesch, 1914)

Fig. 8 , 9

Parantipathes (?) tristicha van Pesch, 1914: 99-101 .

Trissopathes tristicha: Opresko, 2003: 511–515 , figs. 9,10.

Types and type locality. ZMA Coel. 3005 (holotype): 3º27’S, 131º0.5’E, western Pacific , Ceram Sea, 567 m.

Material examined. ERG –024–22, Rio Grande Rise, 30º46’35.4”S, 35º3’35.64”W; 1600 m, dredge ( MNRJ 8601, two fragments). ERG –225, Rio Grande Rise, dredge, 31º0’42.12”S, 35º48’11.16”W; 1100–1500 m, date: 07/02/2012 ( MNNRJ 8581, one fragment). ERG -005, SA-MAR ECO /Marion Dufresni, Rio Grande Rise, dredge, 30º0’33.84”S, 36º8’37.32”W; 1280–1380 m, date: 24/06/2011 ( MNRJ 8590, one fragment).

Diagnosis. Corallum sparsely branched; pinnulate and subpinnulate. Primary pinnules in four rows; two rows on the anterior side of the axis and two posterolateral rows. Pinnules in anterior rows oftem aligned such that they appear as a single row when branch is viewed in cross section. Secondary pinnules present only on anterior primary pinnules, and arranged bilaterally; usually suboppositely, but sometimes offset to varying degrees. Two or more pairs of secondary pinnules on each anterior pinnule. Tertiary pinnules absent. Posterolateral primary pinnules mostly 1–1.5 cm long and inclined distally relative to the branch. Anterior primary pinnules mostly 0.5 cm in length, but sometimes as long as posterolaterals. Secondary pinnules lying in the same plane as the anterior primary pinnules on which they occur and of varying length, with basal ones (relative to the direction of the anterior pinnule) longest, and sometimes nearly as long as posterolateral primary pinnules. Pinnular spines simple, smooth, conical to acicular, inclined distally; up to 0.28 mm tall from center of base to apex (largest ones usually on secondary pinnules); arranged in irregular axial rows, three to five of which can be seen in lateral view; with two to three spines per millimetre in each row. Spines reduced in size on branches and stem. Polyps unknown ( Opresko, 2003).

Description of Brazilian specimens. Four fragments branched up to fifth order, and pinnulated, with branches occurring mainly in one plane ( Fig. 8a ). Angle of insertion of the branches of approximately 50 ° toward the distal end of the coral. Pinnules arranged in four rows, two posterior/lateral rows and two anterior rows. Anterior rows of primary pinnules aligned, appearing to form a single row. Length of posterolateral primary pinnules up to 20 mm, usually between 7 and 10 mm, inclined toward the distal end, with distal angle between 50° and 80° ( Fig. 8b ). Length of anterior primary pinnules usually between 3 and 7 mm, up to 10 mm. Diameter close to the base of the posterolateral pinnules between 0.17 and 0.4 mm, usually between 0.2 and 0.3 mm. Distance between cycles of posterolateral pinnules mainly of 1.5 to 2.5 mm, reaching 4 mm. Number of primary pinnules per centimetre between 10 and 15, but up to 18 per centimetre in MNRJ 8581. Subpinnules occurring on the anterior primaries, number of 2 to 6 per anterior primary pinnule, appearing in sub-opposition, rarely alternately. Length of secondary pinnules up to 12 mm in specimen MNRJ 8590. Basal diameter of secondary pinnules up to 0.5 mm in specimen MNRJ 8601. Tertiary pinnules were absent in all analyzed samples. Angle of insertion of the secondary pinnules on the anterior primary of 80° to 120°. Conical spines, inclined towards the distal end of the pinnule, arranged in three to four rows visible in lateral view ( Fig. 8 c–d). Size of spines usually varying between 0.05 and 0.07 mm, but up to 0.15 mm. Width of the base of the spines varying between 0.06 and 0.2 mm. Distance between spines of the same row variable, usually near to 0.6 mm. Polyps not visualized (lost tissue).

Remarks. The specimens described here as Trissopathes cf. tristicha differ from Trissopathes sp. (MNRJ 8596) especially in the size of the spines. In MNRJ 8596 the spines reach up to 0.05 mm in height, whereas in the specimens described here as Trissopathes cf. tristicha spines were observed reaching up to 0.15 mm on anterior and secondary pinnules. As described for Trissopathes tristicha (see Opresko, 2003), the material from the Rio Grande Rise presents anterior pinnules with up to 6 subpinnules. However, the spines of our specimens are smaller than those in the type of T. tristicha (up to 0.15 mm in T. cf. tristicha , and up to 0.225 mm in the holotype). These differences may indicate the existence of a wide range of variation in the size of spines for species of the genus Trissopathes . Lastly, Trissopathes cf. tristicha differs from Trisopathes tetracrada and Trissopathes pseudotristicha mainly in subpinnulation pattern, a characteristic that is diagnostic for species of the genus (see Table 1 ).

Distribution. Philippines and South Australia ( Van Pesch, 1914; Opresko, 2003) and southwestern Atlantic, Rio Grande Rise (herein) ( Fig. 9 ); from 430 m ( Opresko, 2003) to 1600 m depths (this work).

Figures

FIGURE 8. MNRJ 8590, MNRJ 8581: Trissopathes cf. tristicha (Van Pesch, 1914). a—(MNRJ 8590)—Corallum morphology; b (MNRJ 8581)—Pinnulation pattern; c (MNRJ 55 8581)—Organization of spines; d (MNRJ 8590)—Spines magnified.

FIGURE 9. Geographic distribution of Genus Trissopathes Opresko, 2003. Yellow circles: records extracted from the literature (Opresko, 2003) and based on Ocean Biogeographic Information System (OBIS). Red circle: record made in the present work.