Kirkegaardia antonbruunae, 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 : 54-56

Kirkegaardia antonbruunae new species

Figures 26 D–E; 27

Material examined. Pacific Ocean, Western South America , off Chile, SW of Valparaiso, R/ V Anton Bruun, Cruise 18A, Sta. 687, 34.12°S, 72.32°W, 730–750 m, coll. 0 5 August, 1966, Menzies trawl, holotype and 1 paratype ( USNM 1407132–3 ) .— Off Peru, South of Lima, R/ V Anton Bruun, Cruise 17, Sta. 660-C, 12°58′S, 077°16′W, 1000 m, coll. 26 Jun 1966, rock dredge, 1 specimen ( USNM 1407134 ) .

Description. An elongate species, body relatively consistent in width throughout; all segments wider than long, no elongate or moniliform segments on any specimen. Holotype and paratype incomplete; holotype 11 mm long, 0.65 mm wide across thorax for 77 setigerous segments; paratype 4.4 mm long, 0.35 mm wide, for 31 setigerous segments. Specimen from Peru mostly complete, 14 mm long, 0.7 mm wide across thorax for ca. 70 setigers. Color in alcohol light tan. Specimen from off Peru with attached tessellated tube material ( Fig. 26 D).

Prostomium narrow, triangular, tapering to bluntly pointed anterior margin ( Figs. 26 E, 27A–B; nuchal organs as curved slits at posterior margin ( Fig. 27 B); eyes absent. Peristomium about as wide as long; ventrally and laterally forming lips around mouth, 3–5 annular rings complete laterally and ventrally, but not cutting across smooth dorsum ( Figs. 26 E, 27A–B). Peristomium ending abruptly at anterior margin of setiger 1 ( Fig. 27 A). Dorsal tentacles positioned in notch between peristomium and anterior medial border of setiger 1 ( Fig. 27 A); low dorsal ridge extends from end of peristomium posteriorly over dorsum of thorax for 5–6 segments before becoming indistinguishable from dorsal surface ( Fig. 27 A). Branchiae first present from setiger 1, arising from posteriormedial border, similar on following segments ( Fig. 27 A); branchiae on all thoracic segments, continuing to at least setiger 30 of abdominal region.

Thoracic region of holotype with 20 setigers, characterized by parapodia elevated over broadly rounded dorsal surface ( Figs. 26 E, 27A); paratype with 15–16 setigers in thoracic region similar in appearance to holotype. Transition from thoracic to abdominal segments somewhat gradual with parapodia shifting to lateral position; thoracic and abdominal segments with weakly developed mid-ventral ridge consisting of a long row of elevated mid-ventral mounds at junction of each segment on venter; these poorly developed on thoracic segments, best developed on abdominal segments; each mount limited to individual segments, not crossing segmental grooves to adjacent segment. Far posterior segments dorsoventrally flattened, not expanded, best observed on specimen from off Peru.

Parapodia low narrow mounds in thoracic segments, becoming wider and more closely spaced in abdominal segments ( Fig. 27 C). Notosetae long, narrow, smooth capillaries throughout, numbering 20 or more per fascicle in thoracic segments and 12–15 in abdominal segments ( Fig. 27 C); abdominal notosetae of specimen from off Peru natatory-like in length ( Fig. 26 D). Neurosetae of thoracic segments and anterior abdominal segments similar to notosetae, both long and silky in appearance; from about setiger 35, neurosetae becoming shorter, thicker ( Fig. 27 C), with fine denticles along margin visible at 400x, but details of denticles best observed at 1000x ( Fig. 27 D– E); denticulate neurosetae numbering up to 18 in a fascicle with setae appearing to be in two rows; denticles directed dorsally toward notosetae.

Pygidium unknown.

Methyl Green stain. No distinct staining reaction, entire body except tip of prostomium staining uniformly light green; body destaining rapidly upon return to alcohol.

Etymology. This species is named for the former research vessel, R/V Anton Bruun upon which the Southeastern Pacific Biological and Oceanographic Program (SEPBOP) program was performed; that program represented the first extensive collection of benthic invertebrates from shelf, slope, abyssal, and trench depths off western South America.

Remarks. Kirkegaardia antonbruunae n. sp. belongs to a group of species related to K. tesselata , K. baptisteae , and K. dutchae n. sp. in having similar morphology and tubes consisting of thin membranous tessellated mucoid materials. Of these, only K. baptisteae has denticulate notosetae and only K. dutchae has a middorsal peristomial ridge. K. antonbruunae n. sp. and K. tesselata , therefore, are most closely related morphologically to one another; both species have a mid-dorsal thoracic ridge, short in K. antonbruunae n. sp. and that are lacking in the other two species. K. antonbruunae n. sp. differs from K. tesselata in having 3–5 prominent peristomial annular rings and abdominal segments with a mid-ventral ridge; both are lacking on K. tesselata . K. antonbruunae n. sp. has no MG staining pattern at all; K. tesselata may have a weak stain on the venter of the thorax. K. baptisteae also lacks a distinct MG staining reaction.

Biology. Kirkegaardia antonbruunae n. sp. has tessellated tube material ( Fig. 26 D) similar to that described for K. baptisteae , K. dutchae , and K. tesselata . No data on the habitat or sedimentology is available. The type vial contained three additional cirratulid species: Aphelochaeta sp. (1 specimen), Cirriformia sp. (5 specimens), and Dodecaceria sp. (15 specimens). The specimen from off Peru was collected with several specimens of a large undescribed species of Aphelochaeta .

Distribution. Continental slope off Peru, 1000 m; off Chile, SW of Valparaiso, 737– 750 m.

Figures

FIGURE 27. Kirkegaardia antonbruunae n. sp., holotype (USNM 1407132): A, anterior end, dorsal view; B, anterior end, right lateral view; C, abdominal parapodium, anterior view; D – E, abdominal neurosetae, insets not to scale.

FIGURE 26. A – B, Kirkegaardia tesselata (Hartman, 1960): A, worm in tessellated tube from off northern California; B, anterior end of same (LACM-AHF Poly 8936). — C, Kirkegaardia giribeti (Dean & Blake, 2009): Anterior end, right lateral view (JAB). — D, Kirkegaardia antonbruunae n. sp., anterior end lateral view of specimen from off Peru showing tessellated tube material (USNM 1407134); E, anterior end of same, dorsal view.