Caulleriella microbidentata, Blake & Dean, 2019

Blake, James A. & Dean, Harlan K., 2019, New Species of Cirratulidae (Annelida, Polychaeta) from the Caribbean Sea, Zootaxa 4671 (3), pp. 301-338 : 310-311

Caulleriella microbidentata new species

Figure 5

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Material examined. Caribbean Sea, Carib 1, R/V Alpha Helix , Honduras, off mouth of channel to Laguna de Caratasca , north west of Barra Kruta, Sta. ND-41-500, 15°43.2ʹN, 83°21.6ʹW, 12 July 1977, subtidal, dredged through grass bed on north bank of channel 1000 m from mouth; depth 10–50 cm, holotype ( USNM 1557505 ) .— Aruba, off Oranjestad in shallow lagoon off west coast of Aruba immediately south of ship channel, Sta. MS-18- 500, 12°30.3ʹN, 70°2.7ʹW, 26 June 1977, epibenthic sled through grass bed just inside barrier island on west side of lagoon, depth 20 cm, 2 paratypes ( USNM 1557506 ) .

Description. Holotype complete, 3.6 mm long for 50 setigers with a maximum width of 0.2 mm; one paratype (USNM 1557506) 2.8 mm long for 54 setigers, 0.2 mm maximum width; second paratype (USNM 1557506) 3.3 mm long for 43 setigers (pygidium absent), width 0.2 mm. Holotype with narrow body, thoracic region slightly dorsoventrally depressed, remainder of body dorsoventrally flattened. Pre-setiger region slightly wider than long ( Fig. 5 A–B). Thorax with 12 setigers, segments narrow, approximately seven times as wide as long. Post-thoracic setigers longer, 1.5 times as wide as long. Last 12 posterior setigers narrowing, approximately twice as wide as long. Color in alcohol light tan.

Prostomium triangular, narrowing to rounded apex; eyespots and nuchal organs not observed; broad mid-dorsal crest extending from prostomium across peristomium and onto setiger 3 ( Fig. 5 A–B). Peristomium with three subequal annular rings, not crossing dorsal crest, best observed laterally; dorsal tentacles arising from dorsal surface of setiger 3 due to posterior extension of dorsal crest ( Fig. 5A ). First pair of branchiae arising dorsal to notosetae of setiger 1 and in a similar position on subsequent setigers ( Fig. 5 A–B). Notopodia and neuropodia conical lobes with setae emerging distally, widely separated from each other, thoracic podial lobes with a weak triangular pre-setal lobe.

Notosetae of setigers 2–5 all capillaries; one acicular hook from setiger 6, subsequent notopodia with 1–2 hooks, hooks accompanied by a single capillary (this capillary occasionally absent); neurosetae of first five setigers 3–4 capillaries; three hooks from setiger 6, accompanied by two capillaries, subsequent neuropodia with 2–3 hooks usually accompanied by single capillary ( Fig. 5C ). Notopodial hooks unidentate; neuropodial hooks with tips divided into two minute, forward-projecting teeth ( Fig. 5D ), bidentate nature difficult to observe at all angles, usually visible only laterally; ventral tooth may be worn giving the appearance of a minute irregularly tipped spine.

No asetigerous segments anterior to the pygidium; pygidium conical, anus ventral.

Methyl Green stain. No pattern; body stains uniformly with the prostomium and pygidium unstained.

Remarks. Caulleriella microbidentata n. sp. is unusual in that the dorsal tentacles emerge from setiger 3, carried posteriorly by the dorsal crest over the dorsum of anterior setigers. This arrangement is similar to that of C. cabbsi Pocklington & Coates, 2010 in which the dorsal crest extends to setiger 2. The two species differ in that C. cabbsi has four peristomial annulations while C. microbidentata n. sp. has only three and the first branchiae occur on setiger 2 in C. cabbsi and on setiger 1 in C. microbidentata n. sp. Additionally, the notopodial hooks first occur on setiger 15–16 and the neuropodial hooks on setiger 10 in C. cabbsi while they both occur on setiger 6 in C. microbidentata n. sp. The unusual, weakly bidentate hooks of C. microbidentata n. sp. are distinct from the clearly bidentate hooks of other species of Caulleriella . They are similar in many respects to those seen in some species of Tharyx Webster & Benedict, 1887 . These two genera, however, may be differentiated by the position of the notopodia and neuropodia: species of Caulleriella have widely spaced noto- and neuropodial setal fascicles ( Fig. 5B ) while in Tharyx the setal fascicles arise close to one another. The hooks of C. microbidentata n. sp. could possibly be misconstrued as simple unidentate spines as seen in species of the genus Chaetozone but they do not form the distinctive cinctures characteristic of Chaetozone ( Blake 2015, 2018).

Etymology. The name is from the Greek, mikros for small and bidentate, for two teeth. The species name refers to the very small bidentate teeth on the neuropodial hooks.

Distribution. Honduras, subtidally off the mouth of the channel to Laguna de Caratasca.

Figures

FIGURE 5. Caulleriella microbidentata n. sp. Holotype (USNM 1557505): A, anterior end, dorsal view; B, anterior end, lat- eral view; C, posterior parapodia, anterior view; D, neuropodial weakly bidentate spine from posterior setiger.