Notopygos megalops McIntosh, 1885

Yanez-Rivera, Beatriz & Carrera-Parra, Luis Fernando, 2012, Reestablishment of Notopygos megalops McIntosh, description of N. caribea sp. n. from the Greater Caribbean and barcoding of " amphiamerican " Notopygos species (Annelida, Amphinomidae), ZooKeys 223, pp. 69-84 : 75-78

Notopygos megalops McIntosh, 1885 reinstated Figure 3

Notopygos megalops McIntosh, 1885: 17-19. Pl. 1, fig. 1, Pl. 2a, fig. 3, 4.

Notopygos crinita Salazar-Vallejo 1997: 384-385 (partim, non Grube 1855).

Type material.

Holotype (juvenile) [BMNH 1885.12.1.12] Bermuda, 32°07' N, 65°04'W, Sta. 36, “Challenger”, April 1873, 55 m. Broken into two parts, damaged (Fig. 1).

Additional material.

[UMML 22.909] Near Jamaica, 17°27'N; 78°10'W, Sta. 1256, "R/V Pillsbury", July 1970, 590 m. [UMML 22.903] Venezuela, 10°57'N, 66°18'W, Sta. 739, "R/V Pillsbury", July 1968, 257m, juvenile (Fig. 1).

Description,

Adult specimen (UMML 22.909) complete with 23 chaetigers, damaged, gut exposed, broken, posterior end in poor condition; body fusiform; 3 cm total length, 1 cm wide in the widest part. Prostomium semicircular without pigmented areas, four eyes. Median antenna lost, in central position of prostomium, lateral antennae and palps of similar length (0.7 mm). With stain, ventral surface of buccal lips conserved the stain displaying a glandular zone (Fig. 3A). Mouth placed ventrally in chaetiger 3.

Caruncle oval (1.9 mm length, 0.8 mm wide), elevated lobe with about seven folds in the middle, a rectangular projection between each fold pair. Lateral lobes narrow, with a slightly folded edge, without pigmentation (Fig. 3B).

Branchiae from chaetiger 6, present throughout body. Each branchia as a tuft of slender branchial filaments. First branchiae with a main stem, with seven branchial filaments; in median chaetigers with a main short stem, branching in four stems with five to seven branchial filaments each (Fig. 3D).

Parapodia biramous, notopodium with double cirri and neuropodium with single ventral cirrus. Accessory cirrus simple, long (2 mm); main cirrus with robust short cirrophore (0.5 mm length) and slender and long cirrostyle (1.5-2.0 mm) in all chaetigers (Fig. 3E). Ventral cirri of similar length (1 mm) along the body, last one smallest (0.7 mm).

Chaetae in noto- and neuropodia of two sizes, short and long. All neurochaetae slender (<0.04 mm wide), long notochaetae (Fig. 3C) twice as thick as short notochaetae. All chaetae asymmetrical furcates; ratio of difference between small and large tines is similar in all chaetae, varying from three to four times.

Anus dorsal in the intersegment 18-19. Posterior end margin with pair of short distal lobes.

Gametes: Unknown.

Distribution.

Greater Caribbean, 55 to 590 m.

Remarks.

Notopygos megalops is characterized by branchiae beginning on chaetiger 6, with four main stems on median chaetigers; anus dorsal in the intersegment 18 -19 and a short caruncle in comparison with other Notopygos species. The caruncle has a wide median lobe with seven wide folds and narrow lateral lobes. McIntosh (1885) indicated that only the cirrophore has a buff pigmentation; the material reviewed, including the holotype, lacks pigmentation, so we cannot corroborate this statement. McIntosh emphasized the serrations of neurochaetae, and the material examined enabled us to clarify that serrations are present in both noto- and neurochaetae on the first chaetigers.

The main attributes that permit us to associate the juvenile described in the original description with the adult forms are the caruncle, the position of the first branchiae, branchial branching, largest notochaeta and the stout cirrophore. McIntosh (1885: 18) described the caruncle as a "usual folded structure, a little more lax than in Chloeia ". In Chloeia the lateral lobes usually are narrower than in Notopygos , which generally are large and flattened. The caruncle in Notopygos megalops has narrow lateral lobes, and relaxed folds in the median lobe (Fig. 3B).

Hartman (1959) suggest that Notopygos megalops is a synonym of Notopygos crinita . Ebbs (1966) pointed out the differentiation in the details of branchial branching discussed by MacIntosh (1855) to differentiate the two species; however, he considered that the differences in chaetae were only minor variations as in other amphinomids. Thus, he supported the statement by Hartman. Salazar-Vallejo (1997), despite having reviewed the holotype of Notopygos megalops , followed Hartman’s opinion and regarded it as a junior synonym of Notopygos crinita .

Only two species of the genus have branchiae beginning on chaetiger 6: Notopygos megalops and Notopygos hispidus Potts, 1909 from the Seychelles. The latter has a complex pigmentation pattern, and a well-developed caruncle with expanded lateral lobes, with about 20 folds and continuous projection between folds in the elevated lobe. In addition, the anus is on chaetiger 21. We consider that there are sufficient features to distinguish Notopygos megalops from the other Notopygos species; thus, we regard it as a valid species.

The caruncle in juvenile specimens is not completely developed; however, the branchiae beginning on chaetiger 6 and the large size of the notochaetae permit species identification.