Solenosmilia australis Cairns & Polonio, 2013, n. sp.

Solenosmilia australis, n. sp.

Figs. 3 J, 13

Solenosmilia variabilis: Squires, 1969: 18, pl. 6, map 2 (in part: record from off Chile).—Cairns et al., 2005: 40, fig. 2J.

Description. The corallum is colonial and bushy, increasing by equal intratentacular budding, producing pairs of equal-sized calices at each branch tip. The holotype is only 3.3 cm tall and 4 cm wide, composed of three pairs of corallites. One of the largest colonies (USNM 1022415) is 6 cm in height. The corallites are cylindrical and circular to slightly elliptical in cross section, often about 7.5 mm in GCD but some as much as 10 mm in diameter. The costae are poorly defined, and the theca is relatively smooth; the corallum is white.

Septa are arranged irregularly in three or four size classes, such as: 8:8:16 (32 septa) or 9:9:18:2 (38 septa). These differences probably reflect the increase in size of a calice before it divides into two smaller corallites. The axial edges of the 8 or 9 primary septa are straight and border the rudimentary columella. The secondary septa are about 0.9 the width of a primary and have slightly sinuous axial edges. The tertiary septa are about 0.5 the width of a primary, and have straight axial edges. Quaternary septa, if present, are rudimentary, confined to the upper corallite near the calice. None of the septa are exsert, and all have relatively smooth septal faces. The fossa is deep and contains a small fascicular columella consisting of 1–4 small, twisted elements. Tabular endothecal dissepiments are common.

Remarks. The only other species in this genus is the well-known cosmopolitan species Solenosmilia variabilis Duncan, 1873. S. australis differs from that species in having larger calices (those of S. variabilis are only about 4– 5 mm in GCD), smoother theca (that of S. variabilis is costate), smaller colonies (those of S. variabilis attain 0.5 m in height), and by having a variable number of non-hexamerally arranged septa (those of S. variabilis are hexamerally arranged). Also, S. variabilis usually lives in association with a commensal eunicid polychaete, and S. australis does not.

Distribution. Off central Argentina and off Peninsula Taitao, Chile, 650–1620 m (Fig. 13).

Material. Holotype: PAT1108DR1, 1 colony, USNM 1192958. Paratypes: PAT0108DR8, 2, MNCN; PAT1008DR8, 1, MNCN; PAT1008DR11, 1, MNCN 2.04/1106: PAT1008DR12, 1, MNCN 2.04/1107; PAT1008DR13, 6, MNCN; PAT1108DR3, 10, MNCN; PAT1108DR9, 2, MNCN; PAT1208DR4, 3, MNCN 2.04/ 1103; PAT1208DR6, 2, MNCN 2.04/1104; PAT1208DR7, 10, MNCN 2.04/1105, and 1 as substrate of Javania antarctica, USNM 1193323; PAT1208DR9, 1, MNCN; PAT1208DR14, 1, MNCN; PAT0209DR5, 2, MNCN; PAT0209DR7, 2, MNCN; PAT0209DR14, 1, MNCN; Vema 17–14RD, 1 colony, USNM 1022415.

Type locality. 44.890°S, 60.028°W (continental slope off Cabo Dos Bahías, Argentina), 650 m.

Etymology. Named australis (Latin for southern), in allusion to its southern hemisphere distribution.