Leocrates rizzoae, Salazar-Vallejo, 2020

Salazar-Vallejo, Sergio I., 2020, Revision of Leocrates Kinberg, 1866 and Leocratides Ehlers, 1908 (Annelida, Errantia, Hesionidae), Zootaxa 4739 (1), pp. 1-114 : 68-70

Leocrates rizzoae n. sp.

Figs 38 , 39

urn:lsid:zoobank.org:act:2D64FB95-619F-47F1-A19C-54B6D11CA155

Leocrates claparedii: Fauvel 1919: 371 ; Fauvel 1932: 61 (non Costa in Claparède, 1868).

Type material. Indian Ocean. Seychelles Islands. Holotype ( USNM 37642 ), International Indian Ocean Expedition , Seychell Islands Program , Sta. F-67, Curieuse Island (= Île Rouge ; 04°16’48” S, 55°44’48” E), SE end, South point of Laraie Bay , 8 m, 24 Feb. 1964, J. Bohlke, coll . One paratype ( USNM 37641 ), International Indian Ocean Expedition, Seychelles Islands Program, Sta. F-103, Amirante Islands, D’Arros Island (05°24’ S, 53°53’ E), off E side, 25–29 m, 8 Mar. 1964, J. Bohlke, D. Dockins, R. Rosenblatt, W. Starck, J. Tyler & K. Hill, coll.

Additional material. Arabian Sea. One specimen ( MNHN A71a), Mission Gravier Djibouti, Recif de la Menagerie, in corals, 7 Jan. 1904 [11 mm long, 2 mm wide]. Two specimens ( MNHN A71b), Mission Gravier 1904, Île Moucha (11°43’ N, 43°11’ E), Gulf of Tadjoura, Djibouti, dredged, 20 m, 13 May 1904, C. Gravier, coll. [10–18 mm long, 2–3 mm wide]. Gulf of Suez. One specimen ( MNHN A360), Mission R.P. Dollfus, Sta. 11, 8 Dec. 1928, R.P. Dollfus, coll. [8.5 mm long, 1.5 mm wide]. One specimen ( MNHN A372), R/V Calypso, Sta. unknown (probably Southern Saudi Arabian coast), Drach, Cherbonnier & Mercier, coll. [6 mm long, 1 mm wide]. India. One specimen ( MNHN A419), Nicobar Islands, R/VInvestigator, Indian Survey, Sta. 593, Paway Island (Pahua, 07°22’ N, 93°37’ E), Bay of Bengal, shore collecting [12 mm long, 2mm wide].

Description. Holotype (USNM 37642), complete, slightly damaged, bent, sigmoid, middle and posterior cirri missing. Body obconic, blunt anteriorly, tapered posteriorly ( Fig. 38A ), 14 mm long, 2.5 mm wide, 16 chaetigers; left parapodium of chaetiger 9 previously removed (not in container), right parapodium of chaetiger 10 dissected (kept in container). Tentacular and anterior dorsal cirri almost complete, others partially broken or missing. Body pale.

Prostomium longer than wide, slightly wider anteriorly ( Fig. 38B ). Lateral antennae with ceratophores distinct, antennae directed ventrally, almost as long as prostomium, slightly longer than palps; palpophores twice longer than palpostyles. Median antenna broken, probably not reaching anterior prostomial margin, inserted between eyes.

Eyes brownish, anterior eyes each 1 / 6 prostomial width, twice larger than posterior ones, slightly emarginate anterolaterally, more distant to each other than posterior round eyes.

Nuchal organs lobes horizontal C-shaped, completely concealed by anterior margin of tentacular belt; lateral ciliated bands narrow, not visible dorsally. Tentacular cirri without tips, longer ones reaching chaetiger 8. Lateral cushions low, entire; longitudinal striae not visible (probably by integument damage).

Pharynx barely exposed ( Fig. 38C ), jaws observed through previous dissection. Lateral vesicles not seen. Anterior margin with irregular constrictions. Dorsal and ventral jaws brownish, exposed, tapered, ventral jaw smaller than dorsal one.

Dorsal cirri as long as body width (including parapodia). Chaetigers 1–4 without notochaetae; notochaetae present along chaetigers 5–16, about 50 per bundle, delicate, some arranged in bundles, notochaetae subdistally denticulate, denticles fine. Notacicular lobes tapered; neuracicular lobes triangular, blunt, slightly longer than wide ( Fig. 38D ). Ventral cirri as long as neurochaetal lobe. Neurochaetae about 20 per bundle, blades bidentate, most missing, decreasing in size ventrally, remaining blades 5–9 times longer than wide, guards approaching subdistal tooth.

Posterior region tapered, almost without cirri. Preanal segment with dorsal cirri twice longer than ventral ones. Pygidium with anus terminal, anal cirri missing.

Oocytes not seen. Gonad fragments are testis; no oocytes were found.

Etymology. This species name is after Alexandra Elaine Rizzo from the Rio de Janeiro State University, a much-appreciated Brazilian colleague, and in recognition of her research activities, especially as a specialist of several polychaete groups, including Hesionidae . The species-group name is a noun in the genitive case ( ICZN 1999, Art. 31.1.2).

Variation. The paratype (USNM 37641) is complete, anterior half depressed, probably by labels, most cirri and chaetal blades missing; anteroventral dissection along mouth to chaetiger 4 previously made, left parapodia of chaetigers 4 and 7 previously removed (missing), right parapodium of chaetiger 10 dissected (kept in container). Body with parallel sides, blunt anteriorly, tapered posteriorly ( Fig. 39A ), 13 mm long, 2 mm wide, 16 chaetigers. Prostomium longer than wide, barely wider anteriorly ( Fig. 39B ); left lateral antenna slightly shorter than prostomium, slightly longer than left palp; palpophores twice longer than palpostyles. Eyes dark brown, anterior ones twice larger than posterior ones, slightly farther apart and anterolaterally emarginate. Notochaetae from chaetiger 5, about 50 per bundle, finely denticulate subdistally; notacicular lobes tapered, neuracicular lobes conical, blunt ( Fig. 39C ); neurochaetae about 30 per bundle; blades bidentate, 4–16 times longer than wide, guards approaching subdistal tooth ( Fig. 39C , insets).

Remarks. Leocrates rizzoae n. sp. resembles L. iris Grube, 1878 from the Philippines and Samoa, reinstated, because they have large eyes, anterior eyes larger than posterior ones, notacicular lobes entire, three times longer than wide, and middle chaetigers with about 30 neurochaetae per bundle. These two species differ in the shape of anterior eyes, and by the size proportions of palpophore to palpostyles; in L. rizzoae anterior eyes are emarginate, and palpophores are twice larger than palpostyles, whereas in L. iris anterior eyes are reniform, and palpophores are 2–3 times longer than palpostyles. The inclusion of the Red Sea specimens is with hesitation because of the condition of the specimens (one dried out, the other collapsed), and better specimens will help clarify its northwestern distributional range.

Distribution. Arabian Sea, the Seychelles, and Nicobar Islands, Indian Ocean, (Red Sea?), in intertidal to 30 m depth in mixed bottoms, including coralline substrates.

Figures

FIGURE 38. Leocrates rizzoae n. sp., holotype (USNM 37642). A. Anterior region, dorsal view. B. Anterior end, dorsal view. C. Anterior end, ventral view. D. Chaetiger 10, right parapodium, anterior view, MGS. Scale bars: A: 0.7 mm, B: 0.5 mm, C: 0.6 mm, D: 0.2 mm.

FIGURE 39. Leocrates rizzoae n. sp., paratype (USNM 37641). A. Anterior region, dorsal view. B. Anterior end, dorsal view. C. Chaetiger 10, right parapodium, anterior view, MGS (insets: upper and lower neurochaetal blades, notacicular lobe). Scale bars: A: 0.8 mm, B, C: 0.3 mm.