Oligobregma Kudenov & Blake, 1978

Mendes, Samuel Lucas Da Silva Delgado, Paiva, Paulo Cesar De & Rizzo, Alexandra E., 2024, First record of Oligobregma Kudenov & Blake, 1975 (Annelida: Polychaeta: Scalibregmatidae Malmgren, 1867) from Brazil with the description of three new species, Zootaxa 5424 (1), pp. 80-98 : 94-95

Key to species of Oligobregma Kudenov & Blake, 1978

1. Acicular spines present on chaetigers 1–2................................................................ 2

- Acicular spines present on chaetigers 1–3 or 1–4.......................................................... 4

2(1). Acicular spines in both rami........................................................................... 3

- Acicular spines only in notopodia................. O. pseudocollare Schüller & Hilbig 2007 (Scotia and Weddel Seas)

3(2). Eyes present, fused into a single shield-shape patch; Prostomial horns digitate........................................................................................... O. oculata Kudenov & Blake, 1978 ( New Caledonia)

- Eyes absent; Prostomial horns rounded.............................. O. aciculata ( Hartman, 1965) (North Atlantic)

4(1). Acicular spines present on chaetiger 1–3................................................................. 5

- Acicular spines present on chaetiger 1–4................................................................ 11

5(4). Acicular spines only in notopodia...................................................................... 6

- Acicular spines in both rami........................................................................... 7

6(5). Two short rounded prostomial horns, directed forwardly; eyes absent.............................................................................................. O. collare ( Levenstein, 1975) (Southern Ocean, Antarctica)

- Two long rounded prostomial horns, directed laterally; eyes present.................................................................................................... O. notiale Blake, 1981 (Southern Ocean, Antarctica)

7(5). Lyrate chaetae from chaetiger 4........................................................................ 8

- Lyrate chaetae from chaetiger 5–6...................................................................... 9

8(7). Neuropodia with a single row of acicular spines on chaetiger 1–3; lyrate chaetae with equal tynes....................................................................................... O. mucronata Blake, 2015 ( Antarctica)

- Neuropodia with two rows of acicular spines on chaetiger 1–2; lyrate chaetae with subequal tynes................................................................................ O. tasmania ( Kierkegaard, 1996) (Tasman Sea)

9(7). Acicular spines with terminal arista; parapodial cirri inflated or asymmetrical, with nipple-like tips..................................................................... O. aristata Blake, 2023 ( Australia, lower continental slope)

- Acicular spines lacking terminal arista; parapodial cirri triangular, with rounded or pointed tips.................... 10

10(9). Parapodial cirri with narrow rounded tip; ventrally, prominent darkly pigmented pairs of nephridia absent.......................................................... O. profunda Blake, 2023 ( Australia, Tasmania to New South Wales)

- Parapodial cirri with pointed tip; ventrally, prominent darkly pigmented pairs of nephridia present............................................................................... O. renuncula Blake, 2023 ( Australia, Coral Sea)

11(4). Acicular spines only in notopodia..................................................................... 12

- Acicular spines present in both rami................................................................... 13

12(11). Prostomium with two rounded horns directed upwards; acicular spines transitional in chaetiger 4, weaker and similar to capillaries.................................. O. tani Wiklund et al. 2019 (Clarion-Clipperton Zone, Pacific Ocean)

- Prostomium with two elongated horns directed laterally; acicular spines strong in chaetiger 4, not transitional to capillaries............................................ O. quadrispinosa Schüller & Hilbig, 2007 (Scotia and Weddel Sea)

13(11). Acicular spines with pointed tips...................................................................... 14

- Acicular spines with curved rounded tips................... O. bakkeni sp. nov. (Espírito Santo Basin, South Atlantic )

14(13). Lyrate chaetae present from chaetiger 3 on neuropodia................................................................................................. O. nonatoi sp. nov. (Santos and Espírito Santo basins, South Atlantic )

- Lyrate chaetae present from chaetiger 4–11 on neuropodia.................................................. 15

15(14). Lyrate chaetae from chaetiger 4–6..................................................................... 16

- Lyrate chaetae from chaetiger 11............. O. whaleyi Wiklund et al., 2019 (Clarion-Clipperton Zone, Pacific Ocean)

16(15). Lyrate chaetae from chaetiger 4–5..................................................................... 17

- Lyrate chaetae from chaetiger 6..................... O. simplex Kudenov & Blake, 1978 (Westernport Bay, Australia)

17(16). Acicular spines present in neuropodia of chaetiger 4....................................................... 18

- Acicular spines absent in neuropodia of chaetiger 4.............. O. bathyala , 2023 ( Australia lower continental slope)

18(17). Proboscis present as a soft, smooth sac-like structure; parapodial cirri conical; parapodial cirri glands with gold coloration, organized in patches within parapodial cirri..................................................................................................... O. brasierae Wiklund et al., 2019 (Clarion-Clipperton Zone, Pacific Ocean)

- Proboscis present as a strong crenulated structure; parapodial cirri triangular to lanceolate; parapodial cirri glands long and tubular, blackish, entangled in posterior chaetigers, always extending towards cirri’s tip....................................................................................... O. cruzae sp. nov. (Santos Basin, South Atlantic)