Kirkegaardia heroae, Blake, James A., 2016

Blake, James A., 2016, Kirkegaardia (Polychaeta, Cirratulidae), new name for Monticellina Laubier, preoccupied in the Rhabdocoela, together with new records and descriptions of eight previously known and sixteen new species from the Atlantic, Pacific, and Southern Oceans, Zootaxa 4166 (1), pp. 1-93 : 62-63

Kirkegaardia heroae new species

Figure 31

Material examined. Argentina, off Tiera del Fuego, Staten Island, R/V Hero Cruise 712, Sta. 665, 54.742°S, 63.882°W, 44 m, 11 May 1971, Petersen grab, holotype and paratype ( USNM 1013894–5 ) ; Sta. 659, 54.858°S, 64.452°W, ca. 33 m, 0 1 May 1971, Petersen grab, 2 paratypes (USNM 1013896).

Description. A moderately sized species, holotype with 39 segments, 4.6 mm long, 1 mm wide across expanded thorax; smaller paratype with 40 setigers, 4 mm long, 0.35 mm wide across thorax. Color in alcohol: light tan, no pigment apparent.

Pre-setigerous region relatively short, 1.3x as long as wide. Prostomium short, triangular, narrowly rounded on anterior margin ( Fig. 31 A–B); nuchal organs not apparent; eyes absent. Peristomium wider than long, with three annulations formed by four grooves; first annulation following prostomium enlarged, expanded laterally; then followed by two narrow rings resembling achaetous segments ( Fig. 31 B); dorsum of these last two rings with elevated crest terminating anteriorly with large peristomial ring and posteriorly at setiger 1, more or less merging with dorsal surface of thoracic segments ( Fig. 31 A–B). Dorsal tentacles arising on third peristomial ring immediately anterior to setiger 1; first pair of branchiae arising posterior to dorsal tentacles in middle of setiger 1; second pair of branchiae also on setiger 1, arising dorsal to notosetae on posterior margin of segment ( Fig. 31 B); subsequent segments with branchiae on posterior margin of segment; branchiae thin, wrinkled, most missing.

Thoracic region with about 28 narrow, crowded segments; broadly swollen from about segments 12–27 ( Fig. 31 A); abdominal segments moniliform; posterior end narrow, expanding in far posterior segments. Dorsum of thoracic region smooth, rounded, without dorsal groove or ridge; venter with deep mid-ventral groove.

Parapodia well developed in thoracic region, forming distinct shoulders, but not elevated over dorsal surface; dorsally parapodia merging indistinctly with dorsal surface; parapodia with reduced setal tori posteriorly. Noto- and neurosetae of anterior setigers long simple capillaries, golden colored, dark at bases, numbering 7–8 per fascicle, decreasing to 4–5 posteriorly; neurosetae broader, thicker than notosetae in first 10–15 setigers; from about setiger 30, noto- and neurosetae with serrated edge formed by separated fibrils ( Fig. 31 C–D), serrations visible at 400x.

Methyl Green stain. Entire body staining uniformly; middle of thorax with 3–4 segments with deeper turquoise band completely encircling body. Intersegmental areas staining darker turquoise.

Etymology. This species is named for the R/V Hero , former research vessel of the U.S. Antarctic Program.

Remarks. Kirkegaardia heroae n. sp. is provisionally assigned to Kirkegaardia n. nom. The noto- and neurosetae are thick and have prominent serrations along one edge, but these are not the denticulate type of seta that characterizes other species of the genus. Among the Antarctic cirratulids examined as part of this study, K. heroae n. sp. is the only species to have such a long thorax with an expanded region. In K. chilensis n. sp., the thorax is also expanded, but only ventrally. The moniliform abdominal segments are more characteristic of some species of Aphelochaeta , such as the type species, A. monilaris (Hartman) and it is possible that K. heroae n. sp. may be reassigned pending further study.

Superficially, K. heroae n. sp. resembles K. araiotrachela n. sp. in overall body shape and in having one large and two small peristomial annular rings. However, the two species have different parapodial morphologies and different kinds of setae.

Distribution. Antarctic Peninsula, in shelf depths.

Figures

FIGURE 31. Kirkegaardia heroae n. sp., holotype (USNM 1013894): A, anterior end, dorsal view; B, same, with more detail; C – D, abdominal neurosetae.