Aglaophamus fabrun, Franco, Natália Bizzo & Rizzo, Alexandra E., 2016

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 : 295-296

Aglaophamus fabrun sp. nov.

Figure 3 (A–E); Figure 8 (A–D)

Type material. 11 specimens: HABITATS: Continental Shelf: Holotype: UERJ 5823 (HAB.17 E1R2, no data); Paratypes: UERJ 4968 (7 spec., HAB.17 E1R2, no data); UERJ 4967 (2 spec., 22º8’4.960’’S and 040º27’33.740’’W, HAB.16 E3R1, 65 m), UERJ 4969 (1 spec., 22º7’38.970’’S and 040º18’52.510’’W, HAB.16 F3R3, 73 m).

Diagnosis. Proboscis with 10 pairs of distal papillae, circa 20 subdistal papillae in rows, each row with 3–5 papillae, and unpaired median papilla absent; prostomium with characteristic pigmentation pattern, a central spot, a pair of small eyes, and another pair embedded on anterior segments (fourth parapodium).

Description. Specimens ranging from 5–22 mm long and 0.6–1 mm wide; with 12–69 chaetigers; some specimens incomplete. Description based on the complete holotype (UERJ 5823) in three parts, with 73 chaetigers, 21.5 mm long, and 0.8 mm wide (excluding chaetae). Body long and slender. Prostomium with anterior and lateral edges slightly rounded; small spot on dorsal central portion ( Figure 3 A–B). Frontal pair of antennae and ventral pair of palps present. One pair of small subdermal eyes ( Figure 3 B) located at base of first chaetiger, near posterolateral edge of prostomium, and another pair embedded on anterior segments (fourth parapodium), occasionally not visible (when stained) ( Figure 3 B). Proboscis with 10 pairs of distal papillae; circa 20 rows, each row with 3-5 subdistal papillae. Pair of rounded nuchal organs situated on first chaetiger. First parapodia well delimited, rudimentary and positioned frontally ( Figure 3 A–B); dorsal and ventral cirri short, slender and rudimentary, as are notopodial and neuropodial lobes. Ventral mouth opening occupying chaetigers 1 to 3. Interramal branchiae curved inward, present from chaetiger 3 ( Figure 3 C–E); decreasing in size toward posterior region until they disappear in final portion of body. Notopodial and neuropodial preacicular lobes rounded, underdeveloped; acicular lobe small and pointed, slightly larger than preacicular; postacicular lobe larger than others, rounded, well developed and translucent ( Figure 3 C–E). Notopodia less developed than neuropodia. Dorsal cirri slender, short; ventral cirri conical and developed, but short ( Figure 3 C–E). Space between notopodia and neuropodia decreases gradually toward posterior chaetigers. Notopodial and neuropodial preacicular chaetae of three kinds: short and barred ( Figure 8 B), short and flattened ( Figure 8 C), and short and serrulate; postacicular chaetae from middle of body of two kinds: long and serrulate ( Figure 8 D), and long capillary ( Figure 8 A). Lyrate chaetae present on all parapodia, but in larger numbers from middle region. Pygidium rounded, small, with short pygidial cirrus.

Remarks. The new species resembles Aglaophamus uruguayi Hartman, 1953 , from Uruguay: both have a pair of subdermal eyes on the posterior margin of the prostomium, the proboscis with 20 rows of subdistal papillae, and chaetae of the same type. In A. uruguayi the rows of subdistal papillae contain 6 to 9 papillae each, a middorsal unpaired papilla is present, and the interramal branchiae start from chaetiger 4. Unlike the other species described from Brazil, Aglaophamus fabrun sp. nov. has the proboscis with 20 subdistal papillae in rows of 3–5, and lacks an unpaired median papilla; also, the prostomium has characteristic pigmentation, with a central dorsal spot, a feature not present in other Brazilian species of this genus. The nervous system appears as two small dark subdermal eyes located at the basis of chaetiger 4, but cannot be seen in all specimens, especially when they are stained and /or juveniles.

Etymology. The species name “ fabrun ’ is dedicated to Fatima Lobôsco Bizzo (“ fa ”) and Bruno Bizzo Franco (“ brun ”), respectively, the mother and brother of the first author, combining the first letters of each name. Distribution. Known only from the Campos Basin, Brazil, in depths of 65– 73 m.

Figures

FIGURE 3. Aglaophamus fabrun sp. nov. Holotype UERJ 4968. (A) Anterior region, dorsal view. (B) Anterior region, dorsal view. (C) Parapodium 13, anterior view. (D) Parapodium 30, anterior view. (E) Parapodium 50, anterior view. (Abbreviations: BR: interramal branchiae; CS: central spot; DC: dorsal cirrus; E: eyes; SE: subdermal eyes; VC: ventral cirrus). A: x 40; B: 0.5 mm; C: x 40; D – E: x 100.

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.