Rhamphobrachium

Paxton, Hannelore & Budaeva, Nataliya, 2015, Minibrachium, a new subgenus of Rhamphobrachium (Annelida: Onuphidae) from Australia with the description of three new species, Zootaxa 4019 (1), pp. 621-634 : 631

Key to subgenera of Rhamphobrachium and species of R. (Minibrachium) n. subg.

1 Peristomial cirri absent; branchiae absent; lower limbate chaetae simple, spinigers absent; subacicular hooks with spiny hoods from chaetiger 3–5, gradually changing to typical subacicular hooks by about chaetiger20....... R. (Minibrachium) n. subg3

- Peristomial cirri and branchiae present; subacicular hooks from chaetiger 10–16.................................... 2

2. (1) Peristomial cirri inserted far apart; lower limbate chaetae pseudocompound to compound (= spinigers); maximum of two subacicular hooks per parapodium; Mx VI absent................................................... R. ( Spinigerium )

- Peristomial cirri inserted close together; all limbate chaetae simple; maximum of three to six subacicular hooks on chaetigers 15–30............................................................................. R. ( Rhamphobrachium )

3. (1) Bidentate distally recurved spiny hooks ( Figs 2 A, 3A–C); two subacicular hooks per parapodium from chaetiger 5..................................................................................... R. (Minibrachium) nutrix n. sp.

- Unidentate distally recurved spiny hooks ( Figs 2 B, 6G–J); 4–10 subacicular hooks per parapodium from chaetiger 3....... 4

4. (3) Subacicular hooks of chaetiger 3 simple ( Fig. 6 D, F); pectinate chaetae with 9–13 very long teeth ( Fig. 6 K).................................................................................................... R. (M.) talboti n. sp.

- Subacicular hooks of chaetiger 3 compound to pseudocompound ( Figs 2 D, E, 5C); pectinate chaetae with 8–10 long teeth ( Fig. 5 G)................................................................................. R. (M.) fractum n. sp.

Figures

FIGURE 2. Rhamphobrachium (Minibrachium) nutrix n. sp. (A, B), R. (M.) fractum n. sp., (C – G) and R. (M.) talboti n. sp., (H – I). A. Distal part of recurved hook from chaetiger 1; B. Subacicular hook from chaetiger 20; C. Anterior part of body; D. Distal part of recurved hook from chaetiger 1; E. Compound subacicular hook from chaetiger 3; F. Pseudocompound subacicular hook from chaetiger 3; G. Simple subacicular hook from chaetiger 4; H. Mandibles; I. Part of maxillary apparatus (MxI, MxII and MxIII are shown).

FIGURE 5. Rhamphobrachium (Minibrachium) fractum n. sp., AM W. 47834.001. A. Anterior part of body, lateral view; B. Parapodia from chaetigers 3 – 5; C. Compound subacicular hooks from chaetiger 3; D. Simple subacicular hooks from chaetiger 4; E. Parapodium from chaetiger 19; F. Simple subacicular hook from chaetiger 23; G. Pectinate chaeta from chaetiger 13; H. Posterior end, dorsolateral view, showing pygidium with anus and anal cirri. Abbreviations: ac = anal cirrus, dc = dorsal cirrus, la = lateral antenna, ma = median antenna, p = palp, vgp = ventral glandular pad.

FIGURE 6. Rhamphobrachium (Minibrachium) talboti n. sp., AM W. 47838.001. A. Anterior part of body, ventral view; B. The same, lateral view; C. Parapodium from chaetiger 3; D. The same, enlarged; E. Parapodium from chaetiger 9; F. The same, enlarged; G. Distal part of recurved hook from chaetiger 1; H – J. Shafts of recurved hooks with movable spines; K. Pectinate chaeta from chaetiger 13. Abbreviations: la = lateral antenna, ll = lower lip, ma = median antenna, mx = maxillae, p = palp, per = peristomium, ul = upper lip, vc = ventral cirrus.