Diopatra mariae, Paxton & Arias, 2017

Paxton, Hannelore & Arias, Andres, 2017, Unveiling a surprising diversity of the genus Diopatra Audouin & Milne Edwards, 1833 (Annelida: Onuphidae) in the Macaronesian region (eastern North Atlantic) with the description of four new species, Zootaxa 4300 (4), pp. 505-535 : 521-523

Diopatra mariae sp. nov.

Figures 7 E–G, 10, 11; Table 1, 2

Material examined. Type material. Holotype: ( MNCN 16.01 /17818), Papagayo beach, Lanzarote , Canary Islands, 28°50’32” N – 13°47’18” W, intertidal, coll. A. Arias, 10 Aug 2011 ; paratype ( MNCN 16.01 /17819), same data as holotype.

Type locality: Eastern North Atlantic, Canary Islands, Lanzarote, Papagayo beach, 28°50’32” N – 13°47’18” W, intertidal.

Diagnosis. Prostomium anteriorly rounded with two subulate frontal lips; antennae to chaetiger 13–15 with seven to nine ceratophoral rings, lateral projections absent; nuchal grooves crescentic; peristomial cirri present. Anterior four pairs of parapodia with bidentate pseudocompound hooks with pointed hoods; with upper subulate and lower knob-like postchaetal lobes. Ventral parapodial lobes absent, ventral cirri on five chaetigers. Subacicular hooks from chaetiger 17; pectinate chaetae with 18–22 teeth; spiralled branchiae, first on chaetiger 4, single filaments from chaetiger 50.

Description. Both types incomplete, holotype 28 mm long for 86 chaetigers, 2.5 mm wide; paratype 6 mm for 30 chaetigers, 0.9 mm wide. Ethanol stored specimen overall very pale brown with some darker pigmentation on prostomium and anterior chaetigers, no distinct colour pattern ( Figs 7 E, F).

Prostomium anteriorly rounded with two subulate frontal lips separated by a small gap ( Fig. 7 E). Ventral upper lips oval with papilla-like median section between lips; lower lip with median section. Palps reaching to chaetiger 3, lateral antennae to chaetiger 15, median antenna to chaetiger 13; ceratophores with six to eight proximal and a longer distal ring, styles tapering to distal end, with fine tips. Ceratostyles with about 20 irregular longitudinal rows of flat sensory buds; buds forming semicircles ( Fig. 10 A) to almost full circles. Nuchal grooves very shallow crescents, hardly visible below contracted peristomium; peristomial cirri slender, twice as long as peristomium, reaching distal tip of palpophores, inserted distally on peristomium, almost lateral to lateral antennae.

First four pairs of parapodia modified, slightly prolonged and directed anteroventrally ( Fig. 7 F). Prechaetal lobe rounded; large subulate upper and short, knob-like lower postchaetal lobes, lower postchaetal lobes equal in length to prechaetal lobe ( Figs 10 B, C, 11A). Prechaetal lobe becoming reduced, absent from chaetiger 8–9. Upper postchaetal lobe becoming smaller but remaining as little knob into posterior region; lower postchaetal knob absent from chaetiger 6. Dorsal cirri subulate, very long, attaining greatest length from chaetiger 5–10, almost half as long as branchial trunk ( Fig. 7 F), thereafter gradually shortening, becoming very slender posteriorly; ventral cirri subulate on anterior five chaetigers, with last being much shorter than preceding ones, thereafter replaced by ventral glandular pads. Ventral lobe absent. Spiralled branchiae ( Fig. 7 E, F) from chaetiger 4, best developed on chaetigers 5–10 with about 12 whorls of short, thin filaments on thin branchial trunk, with length of trunk almost equalling body width. Thereafter length of branchiae and number of filaments decreasing gradually ( Fig. 10 D, E), single filament from chaetiger 50, absent shortly thereafter.

Modified parapodia (chaetigers 1–4) with one to two slender upper simple limbate chaetae and pseudocompound bidentate hooks with pointed hoods and shafts with two rows of tiny spines ( Fig. 11 A). Each parapodium with one median thicker hook ( Fig. 11 B) and two to three more slender ones ( Fig. 11 C) from main pocket, and one to two very slender hooks Fig. 11 D) from lower position.

Unmodified parapodia (chaetigers 5 onwards) with pectinate and limbate chaetae. Pectinate chaetae slightly oblique with 18–22 teeth ( Figs 10 F, 11E), about 10 in median body region. Limbate chaetae becoming coarsely serrated by chaetiger 30–40; lower limbate chaetae replaced by bidentate subacicular hooks from chaetiger 17 ( Fig. 11 F).

Mandibles and maxillae completely withdrawn in holotype; maxillary formula of paratype ( Fig. 7 G): MI = 1+1; MII = 7+6; MIII = 6+0; MIV = 14+11; MV = 1+1. Tube typical of genus with inner secreted layer and outer layer of foreign particles consisting mainly of algae and vegetal material.

Etymology. It gives us great pleasure to name the new species in honour of Mrs. María Jesús Rodríguez.

Remarks. Postchaetal lobes are well developed in the anterior parapodia of onuphids and occur in most cases singly in a median to dorsal or upper position. However, in some species of Diopatra a ventral knob may extend from the lower part of the postchaetal lobe to the prechaetal lobe, forming a ventral protrusion (or short lower postchaetal lobe) as in D. mariae sp. nov. ( Fig. 11 A) or when longer and subulate, form a lower postchaetal lobe that is only slightly shorter than the upper postchaetal lobe (see D. mellea sp. nov. described below ( Fig. 15 B); for detailed discussion see Paxton (1998). Diopatra mariae sp. nov. and D. mellea sp. nov. bring the number of Diopatra species with double postchaetal lobes to eight ( Table 2). In four of these ( D. biscayensis , D. dexiognatha , D. kristiani and D. sugokai ) the upper and lower postchaetal lobes are both subulate, while in D. chiliensis , D. gesae and the two new species the lower postchaetal lobes range from knob-like to subulate. The former two species can easily be distinguished from the latter two by their unique features: D. chiliensis has extremely oblique pectinate chaetae and D. gesae has mandibles with a ventral bulge. Furthermore, the anterior hooks are uni- to bi- and even tridentate while those of the two new species are bidentate only; other differences are detailed in Table 2. The two new species from the Canaries can be distinguished from each other in that in D. mariae sp. nov. all lower postchaetal lobes are knob-like, ceratophoral rings number 7–9, pectinate chaetae have 18–22 teeth and limbate chaetae are coarsely serrated, while D. mellea sp. nov. has knob-like and subulate lower postchaetal lobes, 12–13 ceratophoral rings, 4–11 teeth on pectinate chaetae and finely serrated limbate chaetae.

Distribution. Diopatra mariae sp. nov. is only known from Lanzarote, Canary Islands.

Figures

FIGURE 7. Diopatra spp. photomicrographs. A, D. madeirensis (MNCN 16.01 / 17816), anterior end, dorsal view; B, D. madeirensis (AM W. 49213) anterior end, dorsal view; C, same, ventral view; D, tube of same; E, D. mariae sp. nov., paratype (MNCN 16.01 / 17819), anterior end, dorsal view; F, D. mariae sp. nov., holotype (MNCN 16.01 / 17818), anterior end, ventrolateral view; G, D. mariae sp. nov., paratype (MNCN 16.01 / 17819) everted maxillae, ventral view.

FIGURE 10. Diopatra mariae sp. nov., holotype (MNCN 16.01 / 17819), scanning electron micrographs. A, Sensory buds of antenna; B, parapodium of chaetiger 4, posterior view; C, same magnified, note lower postchaetal lobe folded onto parapodium; D, parapodium of chaetiger 20, anterior view; E, parapodium of chaetiger 42, anterior view; F, pectinate chaetae. Abbreviations: a, aciculae, b, branchia, dc = dorsal cirrus, = limbate chaeta, lPCL = lower postchaetal lobe; p = pectinate chaeta, PrCL = prechaetal lobe; SAHs = subacicular hooks; uPCL = upper postchaetal lobe; vc = ventral cirrus.

FIGURE 11. Diopatra mariae sp. nov., holotype (MNCN 16.01 / 17819), line drawings. A, Parapodium from chaetiger 2, anterior view; B, median robust pseudompound hook from chaetiger 2; C, upper slender pseudocompound hook from same; D, lower very slender pseudocompound hook from same; E, pectinate chaeta from chaetiger 42; F, subacicular hook from same. Abbreviations: lPCL = lower postchaetal lobe; uPCL = upper postchaetal lobe.

FIGURE 15. Diopatra mellea sp. nov., paratype (AM W. 94216), line drawings. A, Left parapodium from chaetiger 2, anterior view, chaetae omitted; B, right parapodium from chaetiger 2, chaetae omitted; C, median robust pseudocompound hook from chaetiger 4; D, upper slender pseudocompound hook from same; E, lower very slender pseudocompound hook from same; F, pectinate chaeta from chaetiger 21; G, pectinate chaeta from same; H, mandibles; I, maxillae. Abbreviations: lPCL = lower postchaetal lobe; uPCL = upper postchaetal lobe.