Caulleriella ecuadoriana, Blake, 2018

Blake, James A., 2018, Bitentaculate Cirratulidae (Annelida, Polychaeta) collected chiefly during cruises of the R / V Anton Bruun, USNS Eltanin, USCG Glacier, R / V Hero, RVIB Nathaniel B. Palmer, and R / V Polarstern from the Southern Ocean, Antarctica, and off Western South America, Zootaxa 4537 (1), pp. 1-130 : 41-45

Caulleriella ecuadoriana new species

Figures 20–21

Material examined. Ecuador, Bahia de Santa Elena, off Salinas , SEPBOP, R / V Anton Bruun, Cr. 16, Sta. 6670, 08 May 1966, scuba, 02°11ʹ28ʺS, 80°56ʹ31ʺW, 8–9 m, holotype ( USNM 1490723 ); off Golfo de Guayaquil , Cr. 18B, Sta. 773, 11 Sep 1966, bottom trawl, 02°43ʹS, 80°33ʹW, 20 m, 2 paratypes ( USNM 1490724 ) .

Description. A small species, holotype 5.1 mm long, 0.21 mm wide across anterior setigers and 0.3 mm wide across middle segments; with about 75 setigerous segments. Both paratypes complete, largest 3.5 mm long with about 76 setigerous segments. Body elongate, narrow, with all segments wider than long; anterior segments about 12 times as wide as long, middle body segments about six times as wide as long. Posterior segments becoming narrower, tapering to pygidium bearing a rounded lobe ventral to anal opening ( Figs. 20B , 21B ). Prominent darkly pigmented heart body visible internally in setigers 3–13 ( Fig. 21A ). Venter of body generally flattened, weakly grooved along entire length including posterior end; low mid-ventral ridge present within groove along most of length; dorsum generally rounded throughout, becoming weakly flattened in far posterior segments. Holotype pale in alcohol, with no separate body pigmentation except darkly pigmented heart body and other blood vessels ( Fig. 21A ). Smaller paratype with numerous darkly pigmented lines, believed to be blood vessels; some within branchiae.

Prostomium triangular, tapering to rounded tip ( Figs. 20A , 21A ); eyespots absent; nuchal organs not observed. Peristomium with three annular rings, best observed laterally, not crossing low dorsal crest ( Figs. 20A , 21A ). Dorsal tentacles arising mid-dorsally on posterior margin of peristomium ( Fig. 20A ). First pair of branchiae lateral to dorsal tentacles, also arising from posterior margin of peristomium ( Fig. 20A ); second pair of branchiae on setiger 1 dorsal to notosetae; branchiae of subsequent segments in same position ( Fig. 20A ); branchiae continuing segmentally to posterior end. Location of first branchiae on peristomium in relation to setiger 1 difficult to discern due to close proximity of second pair of branchiae on setiger 1.

Noto- and neuropodia widely separated from one another laterally. Parapodia all low tori from which setae arise. Notopodia with capillaries throughout, numbering 5–6 in anterior segments; bidentate hooks from setiger 20, numbering 3–4 per fascicle with 2–3 capillaries through middle segments, reduced to 2–3 hooks and 1–2 capillaries in far posterior setigers. Neuropodia with six hooks from setiger 1 accompanied by 2–3 capillaries; hooks reduced to 3–4 in middle and posterior segments with 1–3 capillaries. Hooks with distinctly curved shafts, with large main fang surmounted by small, but sharply pointed apical tooth ( Figs. 20C , 21C ); hood or sheath absent.

Methyl Green stain. Body more or less staining uniformly; prostomium staining lightly with numerous small speckles. Grooves of peristomial annular rings staining.

Etymology. The species name is derived from its collection from low water offshore Ecuador.

Remarks. Six species of Caulleriella with neuropodial hooks from setiger 1 and lacking eyespots have now been reported from the eastern Pacific ( Blake 1996, Dean & Blake 2007) plus C. suroestense n. sp. and C. ecuadoriana n. sp. reported in the present study. Caulleriella ecuadoriana n. sp. differs from all the others by having the first pair of branchiae on the posterior margin of the peristomium lateral to the dorsal tentacles instead of near the posterior border of setiger 1 dorsal to the notosetae.

Distribution. Known only from off Ecuador in shallow water, 8– 20 m.

Figures

FIGURE 20. Caulleriella ecuadoriana n. sp. Holotype (USNM 1490723): A, anterior end, dorsal view; B, posterior end, left lateral view; C, neuropodial bidentate hook.

FIGURE 21. Caulleriella ecuadoriana n. sp. Photomicrographs of holotype (USNM 1490723): A, anterior and middle setigers, dorsal view; B, middle and posterior setigers, dorsal view; C, neuropodial bidentate hook. Stained with Shirlastain A.