Blastopathes

(Figures 2 – 8; Tables 1 – 2)

Description. The holotype is a 1.2 m tall specimen that branches to the third order (Figure 4). The stem is 0.6 m in length, 6.3 mm in diameter near the base, and 4 mm in diameter just below the first branch cluster. First branch cluster occurs at the apex of the stem and consists of 10 elongate branches extending in different directions (Figure 5 A) of varying lengths (maximum length 1.3 m) and diameters (none thicker than the stem). One first order branch is 0.6 m in length, 4 mm in diameter near the base, and 2 mm in diameter just below a second order branch cluster consisting of ~ 10 branches (Figure 5 B), with a maximum branch length of 50 cm. Another first order branch is 1.3 m in length, 3 mm in diameter near the base, and 0.5 mm at the branch tip and does not produce a branch cluster. Another first order branch extends from the center of the branch cluster and extends 0.9 m directly upwards with a branch thickness of 4 mm near the base and 2 mm just below a second order branch cluster consisting of four branches with a maximum branch length of 65 cm. Another first order branch extends 5 cm, is 2 mm in diameter near the base and increases to 2.5 mm just below what resembles a new branch cluster consisting of three branches of different lengths and thicknesses. The longest of the three branches coming from the 5 cm branch is 0.6 m in length, 1.5 mm in diameter near the base, and 0.5 mm diameter near the tip. The second longest branch is 0.42 m in length, 0.2 mm in diameter near the base, and 0.1 mm near the tip. The shortest of the three branches is 5 cm in length, 0.8 mm in diameter near the base, and <0.1 mm near the tip. Branchlets are found on all branch clusters (Figure 5 B) and locations on branches that seem to be newly forming branch clusters (Figure 5 C) ranging from 1 cm to 8 cm in length, with ~ 0.5 mm diameters at their bases and <0.5 mm diameters at branch tips. The spines (Figures 6 A – 6 C) on the branches and stem are smooth and laterally compressed. Polypar spines are 0.2 mm – 0.34 mm tall, are conical at right angles to branch axes with rounded apexes, and spines are spaced ~ 0.45 mm in one row (Figure 6 A). Abpolypar spines are 0.12 mm – 0.24 mm tall and are triangular with distally slanted proximal edges and perpendicular or proximally slanted distal edges, and spines are spaced ~ 0.38 mm in one row (Figure 6 B). Seven to eight, sometimes offset rows of spines can be counted in one view of a branch and stem, and approximately three spines can be counted in 1 mm of a spine row on a branch (Figure 6 C) and stem. The polyps (Figures 7 A – 7 B), olive in color when alive, are arranged in a single row on thin branches (Figure 7 A), and in multiple rows on the stem and thick branches (Figure 5 A). In-situ measurements reveal that lateral tentacles (~ 3 mm in length, extended) are less than half the length of sagittal tentacles (~ 8 mm in length, extended) (Figure 7 A). Polyps range 0.5 mm – 1.38 mm in transverse diameter and are spaced ~ 1 mm apart, resulting in approximately five polyps per 1 cm in one row (Figure 7 B). The sizes of contracted and extended polyps are quite variable. The paratypes (Figures 8 A – 8 E) range from 0.4 m to 0.5 m in height. The stem lengths range from 3 to 10 cm in length from basal plate to the first branch cluster. All paratypes have branch clusters (Figures 8 A – 8 C), 7 to 8 rows of compressed spines, tall and conical polypar spines, and triangular distally slanted abpolypar spines (Figure 8 D), with polypar spine heights ranging from 0.14 mm to 0.3 mm and abpolypar spines ranging from 0.1 mm to 0.2 mm. About five polyps per 1 cm with lateral tentacles less than half the length of sagittal tentacles, with varying polyp sizes like the holotype (Figure 8 E).

Diagnosis. Corallum sparsely branched to the third and sometimes fourth order, not pinnulate. Branches long (up to 1.3 m) and spaced far apart (distances between first order branches and second order branches range from 210 cm to 560 cm) and occurring singly or in verticil-like clusters of varying numbers (as many as 10). Stem and branches thick (up to 6 mm diameter) and rigid. Each branch extending out at their base perpendicular to the stem and lower order branches from which they arise, and then curving upward with distal ends being straight or curved. One branch can extend directly upwards from the center of the cluster. Spines triangular or conical, laterally compressed, smooth, up to 0.34 mm tall. Polyps, ~ 1.25 mm in transverse diameter, ~ 6 polyps per cm in one row. Sagittal tentacles (~ 8 mm in length, extended) are more than twice the length of lateral tentacles (~ 3 mm in length, extended).

Remarks. Blastopathes morphologically resembles Allopathes Opresko & Cairns, 1994, which also has stemlike branches coming from a singular location on the corallum (Opresko & Cairns 1994). However; Blastopathes differs from Allopathes by having branch clusters that do not necessarily occur near the base of the stem and in having more than one branch cluster (Figures 2 A – 2 B). Additionally, the abpolypar spines of Blastopathes are triangular, smooth, and distally slanted while all spines of Allopathes are conical with conical tubercles near the apex (Figures 2 C – 2 D). Other genera that contain sparse and elongate branches are Pteropathes Brook, 1889, Hillopathes van Pesch, 1910, and in the genus Antipathes, Antipathes dichotoma Palla, 1766; however, none contain branch clusters. Lastly, Blastopathes contains a stiff and non-pinnulate stem and branches that resemble unbranched genera Pseudocirrhipathes Bo et al., 2009, Cirrhipathes de Blainville, 1830, and Stichopathes Brook, 1889, all of which differ from Blastopathes by lacking branches. Molecular results. The mitochondrial igrN sequences for specimens NMAG 1893 and NMAG 1895 consisted of 482 base pairs. The two specimens shared identical sequences across 465 comparable bases. The complete igrN alignment consisted of 47 sequences, 682 bp, and included species from all seven black coral families. In the 682 bp alignment there were 274 parismony informative site (40 %). Targeted capture data for 33 specimens that spanned six of the seven families in the Antipatharia, resulted in a total number of raw reads ranging from 44,898 to 3,603,888. One sample (10 raw reads, C 705) was removed due to sequencing failure. Quality control and adapter trimming resulting in a mean of 1,606,997 ± 1,640,018 SD trimmed reads per sample. Trimmed reads were assembled into a mean of 927 ± 154 SD contigs per sample. The total number of matched UCE / exon loci was 2,309 with an average base pair length of 752 (ranging from 83 to 18,423 base pairs). The 75 % taxon occupancy matrix included 286 loci that were concatenated into an alignment with a total length of 111,929 base pairs. A total of 36,052 parismony informative (PI) sites were identified (32 % of total sites), with an average of 126.06 PI sites per locus. Alignment were also constructed for the for the holotype specimen (MTQ G 74904) and the two paratype specimens (NMAG 1893 and NMAG 1895). The total number of matched loci across the three samples was 1,290 with an average base pair length of 623 (ranging from 189 to 4,068 bp). A complete (all three samples present in each loci) concatenated matrix included 792 loci, with a total alignment length of 499,264 base pairs. There were 3,855 variable sites (~ 0.7 % of total sites) among the three samples. Despite the difference in species-level sampling, the maximum likelihood phylogenies displayed similar topologies for both alignment types (igrN, UCE / exon). In both cases, the new genus formed a distinct clade within the family Antipathidae and members of the genera Cirrhipathes and Antipathes formed separate monophyletic groups (Figures 3 A – 3 B). Differences between the two trees include the UCE / exon tree suggesting that Arachnopathes Milne Edwards H., 1857, and Stichopathes also share a common ancestor with Blastopathes, while in the igrN tree Stichopathes is more closely related to another lineage containing members of the Aphanipathidae Opresko, 2004, than to Blastopathes.

Etymology. From the Greek “ blastos ”, germ, sprout, or shoot, in reference to the branch cluster features, and the commonly used suffix “ pathes ”. From the Latin “ Medusa ” in reference to thick and upward curving branches, like the snakes on the mythical gorgon’s head.

Type material. Holotype, MTQ G 74904, Papua New Guinea, Bismarck Sea, West New Britain Province, Kimbe Bay, Vanessa’s Reef, 35 m depth, 13 March 2019 (SEM stubs MTQ G 74906 to MTQ G 74910, schizo- holotype NMAG 1892). Paratypes, NMAG 1893, Papua New Guinea, Bismarck Sea, West New Britain Province, Kimbe Bay, Christine’s Reef, 30 m depth, 13 March 2019; MTQ G 74911, Papua New Guinea, N Bismarck Sea, West New Britain Province, Kimbe Bay, Lady Di, 37 m depth, 15 March 2019 (SEM stub MTQ G 74912); MTQ G 74913, Papua New Guinea, Bismarck Sea, West New Britain Province, Kimbe Bay Restrf Island, 30 m depth, 16 March 2019 (SEM stub MTQ G 74915); NMAG 1895, Papua New Guinea, Bismarck Sea, West New Britain Province, Kimbe Bay, Christine Reef, 30 m depth, 16 March 2019. Type locality. Kimbe Bay, Papua New Guinea. Latitude: - 5.305; Longitude: 150.124