Aglaophamus juvenalis (Kinberg, 1866)

Franco, Natália Bizzo & Rizzo, Alexandra E., 2016, Nephtyidae (Annelida: Polychaeta) from the Campos Basin, including two new species and a new record, Zootaxa 4114 (3), pp. 291-308 : 297-298

Aglaophamus juvenalis (Kinberg, 1866)

Figure 4 (A–C); Figure 8 (E–G)

Aglaopheme juvenalis Kinberg, 1866: 240 .

Aglaophamus juvenalis Fauchald 1976: 16 –18, Figure 1 ; Lana 1986: 143 –144, Figures 16–17; Rizzo & Amaral 2007: 255 –256, Figure 1 .

Material examined. 7 specimens: AMBES: Slope: UERJ 4575 (2 spec., 19º45’54.71’’S and 039º30’24.91’’W, AMB 12 D4 R3). Continental shelf: UERJ 4549 (5 spec., 20º34’34.37’’S and 040º20’50.77’’W to 20º34’29.6’’S and 040º20’54.56’’W, AMB 14 B1 R2, R3).

Type-locality. Rio de Janeiro, Brazil; collected in the shallow sublittoral (2–3 m depth).

Diagnosis. Proboscis with long unpaired middorsal papilla, 16 rows of subdistal papillae, with 4–6 papillae in each row, and 10 paired distal papillae; interramal branchiae from parapodium 3.

Description. Based on complete specimen (UERJ 4549), measuring 26 mm long and 2.1 mm wide (excluding chaetae), with 70 chaetigers. The remaining specimens, some incomplete and others complete, measuring 3.1–16.8 mm long and 1–2 mm wide, with 29–50 chaetigers. Body robust and cylindrical in anterior region, slender and rectangular in cross section from middle region. Prostomium trapezoidal, wider than long, with dorsal pair of tapered antennae, inserted frontally ( Figure 4 A) and ventral pair of tapered palps. Pair of conical nuchal organs located on posterior edge of prostomium. Proboscis everted, with 10 pairs of distal papillae, long unpaired middorsal papilla, and 16 rows of subdistal papillae, each row containing 4–6 papillae. Some individuals with pair of small subdermal eyes located at base of third parapodium ( Figure 4 A). Interramal branchiae curved inward, present from chaetiger 4, disappearing on posterior parapodia ( Figure 4 B, C). First parapodium inserted frontally, little developed ( Figure 4 A), with short dorsal and ventral cirri; notopodial cirri slightly smaller than neuropodial cirri. Anterior parapodium with notopodia and neuropodia little developed; preacicular lobe rounded and small; acicular lobe conical and larger than preacicular lobe; postacicular lobe translucent, rounded and larger than the others; dorsal and ventral cirri foliaceous. Middle parapodium with notopodial and neuropodial lobes well developed; preacicular lobe rounded and well developed; acicular lobe conical; postacicular lobe rounded and larger than others; dorsal cirri becoming digitiform, long and slender ( Figure 4 B) and ventral cirri becoming short. Posterior parapodium with preacicular notopodial and neuropodial lobes rounded; acicular lobe conical; postacicular lobe rounded and smaller than acicular lobe; dorsal cirri becoming rudimentary ( Figure 4 C), and ventral cirri becoming slender and short. Notopodial and neuropodial preacicular chaetae of two types: long and barred ( Figure 8 F) or capillary. Notopodial and neuropodial postacicular chaetae capillary ( Figure 8 G), more numerous on posterior parapodia than on anterior parapodia; some chaetae serrulate, others lyrate ( Figure 8 E). Pygidium rounded, small, with long pygidial cirrus (about as long as last 5 parapodia together).

Remarks. As described by Fauchald (1976), the specimen examined has dorsal cirri on the first parapodia, although they are short and little developed, differing from the report of Rizzo & Amaral (2007), where such cirri were not found on the first parapodium. In the present specimens, the interramal branchiae are present from the third chaetiger, while in those examined by Fauchald (1976) and Rizzo & Amaral (2007) the branchiae began on parapodium 4. The number of subdistal and distal papillae in the pharynx is an important character for the identification of species of Aglaophamus . Aglaophamus uruguayi resembles A. juvenalis in that both have a proboscis with 20 paired distal papillae, but the number of subdistal papillae distinguishes these species: whereas A. uruguayi has the proboscis with 20 rows of 6-9 subdistal papillae in each row, A. juvenalis has 16 rows of subdistal papillae, each row containing 4-6 papillae.

Distribution. Southeastern Brazil, from Rio de Janeiro to Paraná ( Brazil) ( Lana 1986; Rizzo & Amaral 2007).

Figures

FIGURE 1. Map of the study area: continental shelf and slope. Project HABITATS.

FIGURE 4. Aglaophamus juvenalis UERJ 4549. (A) Anterior region, dorsal view. (B) Parapodium 19, anterior view. (C) Parapodium 40, anterior view. (Abbreviations: BR: interramal branchiae; DC: dorsal cirrus; SE: subdermal eyes). A: 0.25 mm; B – C: x 40.

FIGURE 8. Aglaophamus fabrun sp. nov. (A) Capillary postacicular chaeta from parapodium 13. (B) Barred preacicular chaeta from parapodium 13. (C) Flattened preacicular chaetae from parapodium 13. (D) Serrulate postacicular chaeta from parapodium 30. A – D: x 400. Aglaophamus juvenalis. (E) Lyrate postacicular chaeta from parapodium 40. (F) Barred preacicular chaeta from parapodium 19. (G) Capillary postacicular chaeta from parapodium 19. E – G: x 400.