Caulleriella minuta, Dean, Harlan K. & Blake, James A., 2007

Dean, Harlan K. & Blake, James A., 2007, Chaetozone and Caulleriella (Polychaeta: Cirratulidae) from the Pacific Coast of Costa Rica, with description of eight new species, Zootaxa 1451, pp. 41-68 : 56-58

Caulleriella minuta sp. nov.

Figures 7 F, 9 A–D.

Material examined. Costa Rica,Golfo Dulce. Holotype: Intertidal, Bahia Golfito, 2 km west of main dock, muddy sand, 8°38'N, 83°10'W, Sep 1986, ( MCZ 67151)(coll: José A. Vargas). Paratypes: Intertidal, Bahia Golfito, 2 km west of main dock, muddy sand, 8°38'N, 83°10'W, Sep 1986, (3 MCZ 67152; 4 UCRMZ 132), (26 HKD).

A small species, holotype 1.7 mm long, 0.2 mm wide for 31 setigers; paratypes range from 0.6–2.2 mm long. Body fragile, uniform in width until posterior setigers, rounded in cross-section throughout. Podial lobes simple, low ridges. Pygidium flattened disc dorsal to terminal anus ( Fig. 9 C). Color in alcohol light tan.

Prostomium tapered to rounded with pair of oval, ciliated nuchal organs at posterior border; peristomium extending dorsally over posterior margin of prostomium; with three subequal annulations, and well-developed dorsal crest extending posteriorly over half of setiger 1 ( Figs. 7 F; 9A B). Dorsal tentacles arising from posterior border of third annulation, with narrow base, abruptly increasing in width (dashed-line illustration, Fig. 9 B); first and subsequent branchiae emerging dorsal to setal bundles on notopodia.

Notopodia and neuropodia widely separated, with weakly differentiated tori. Notosetae 4–8 per falciger with laterally fimbriated capillaries in anterior region, joined by a single, bidentate hook at setiger 10 in holotype (9–14 in other specimens) increasing to 2–3 bidentate hooks accompanied by two long, sparsely fimbriated capillaries then, in far posterior segments, setae reduced to single hook and capillary ( Fig. 9 D).

Neuropodia with bidentate hooks from setiger 4 in holotype (4–5 in other specimens), with 1–2 hooks at first accompanied by 3–4 laterally fimbriated capillaries; by setiger 8, four hooks present accompanied by 1–2 laterally fimbriated capillaries; by setiger 10, 4–5 bidentate hooks arranged in single row with no accompanying capillaries; then reduced to 2–3 hooks posteriorly ( Fig. 9 D). Notopodial and neuropodial hooks bidentate with dorsal tooth subequal to or smaller than main fang.

Methyl Green staining pattern. Body staining uniformly light green throughout; prostomium unstained.

Habitat. Known only from intertidal muddy sands of Golfito, Costa Rica

Remarks. Caulleriella minuta sp. nov. is a very small species that resembles Caulleriella bioculata ( Keferstein, 1862) in the presence of capillary setae on all notopodia and in the first appearance of the neuropodial hooks. In C. minuta sp. nov., the first neuropodial hooks occur from setiger 4 with the first notopodial hooks from setiger 10, whereas in C. bioculata the first neuropodial and notopodial bidentate hooks occur from setiger 20. C. bioculata has capillary neurosetae in setigers 1–2, but they are replaced by only hooks (either sharply bent or bidentate) in the following segments, whereas, capillary setae are present in all neuropodial setal fascicles in C. minuta sp. nov. Additionally, C. bioculata is a much larger species with a more elongate body form and the pygidium has a pair of digitiform lobes.

Etymology. This specific name is from the Latin minutus, meaning small and refers to the diminutive size of this species.

Figures

FIGURE 7. Chaetozone nicoyana sp. nov. A. anterior end, lateral view B. posterior neuropodial setal bundle, anterior view. Caulleriella cucula sp. nov. C. anterior end, lateral view. D. neuropodial setal bundle, anterior view. Caulleriella dulcei sp. nov. E. anterior end, dorsal view. Caulleriella minuta sp. nov. F. anterior end, lateral view. no = nuchal organ, s = subacicular tooth.

FIGURE 9. Caulleriella minuta sp. nov. A. Lateral view of anterior end B. Dorsal view of anterior end C. Pygidial region, ventral view D. Posterior setiger, anterior view. Scale bars: A – C = 0.02 mm, D = 0.05 mm. a = annulations, dt = dorsal tentacle, no = nuchal organ.