Kirkegaardia giribeti ( Dean & Blake, 2009 ) Dean & Blake, 2009

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 : 52-54

Kirkegaardia giribeti ( Dean & Blake, 2009) new combination

Figure 26 C

Monticellina giribeti Dean & Blake 2009: 116 –117, Figs.6 B, 8A–F.

Material examined. Pacific Ocean, off Ecuador, Gulf of Guayaquil , R/ V Anton Bruun, Cruise 18B, Sta. 771-D, 03°16′S, 080°47′W, ca. 90 m, 10 Sep 1966, 1 specimen (JAB).

Description. A single, incomplete specimen from off Ecuador closely resembles Kirkegaardia giribeti presently known only from intertidal depths on the Pacific coast of Costa Rica. Ecuadorian fragment 4 mm long, 0.6 mm wide with 33 setigerous segments.

Pre-setigerous region 2.75x as long as wide. Prostomium short, narrow, and rounded on anterior margin; nuchal organs not observed. Peristomium 2.5x as long as wide and cut with four lateral grooves producing five annulations ( Fig. 26 C); low mid-dorsal ridge present along peristomium from anterior to posterior margin. Dorsal tentacles arise from posterior margin of peristomium with first pair of branchiae also on posterior margin of peristomium lateral to tentacles. Second and subsequent pairs of branchiae on posterior margin of each setiger, dorsal to notochaetae on dorsal most edge of parapodium.

Thoracic region with 25 narrow setigerous segments with parapodia shifted dorsally overlying a wide dorsal channel, each segment clearly demarcated ( Fig. 26 C). Transition to abdominal segments abrupt, parapodia shifting laterally, dorsal channel disappearing, and dorsum merging with lateral sides of each segment. First seven abdominal segments narrow, the last becoming longer and more moniliform.

Parapodia low ridges or mounds from which setae emerge. Thoracic notosetae numbering 6–8 long, smooth capillaries becoming wider and shorter in abdominal segments and developing fine serrations along margin; neurosetae with 5–7 smooth setae in thoracic region transitioning to shorter setae with a broad base in abdominal segments also with fine serrations along margin.

Nature of middle and posterior segments not known.

Methyl Green stain. The body stains uniformly light green, with no areas of stain concentration or any pattern evident after differentiation.

Remarks. This specimen agrees with K. giribeti from Costa Rica in most respects including the shape of the prostomium, long narrow peristomium, location of the dorsal tentacles and first pair of branchiae, nature of the thoracic parapodia, and the lack of any MG staining pattern. Differences include five peristomial annulations and a longer thoracic region with 25 setigerous segments in the Ecuadorian specimen instead of six peristomial annulations and 16 thoracic setigerous segments as in the Costa Rican material. However, the Ecuadorian fragment appears to be a larger specimen than the type materials and as such a longer thoracic region is to be expected. The last available abdominal segment on the Ecuadorian specimen is clearly rounded and becoming moniliform which agrees with the original description of moniliform abdominal segments.

Distribution. Costa Rica, intertidal; Off Ecuador, shallow subtidal.

Figures

FIGURE 6. Kirkegaardia annulosa (Hartman, 1965), photomicrographs of specimens from off Georges Bank showing Methyl Green staining pattern: A, right anterior view; B, left anterior view of another specimen; C, detail of abdominal region of same; D, Cross section through thoracic region of a specimen from off Georges Bank. (USNM 140758).

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.