Leocrates bitungensis, Pamungkas, 2024

Pamungkas, Joko, 2024, Leocrates bitungensis (Hesionidae, Annelida): a new polychaete species from North Sulawesi, Indonesia, Raffles Bulletin of Zoology 72, pp. 194-202 : 197-201

publication ID	https://doi.org/ 10.26107/RBZ-2024-0016
publication LSID	lsid:zoobank.org:pub:E854C045-0226-4A51-BC8E-D1F28AE638F3
persistent identifier	https://treatment.plazi.org/id/437B87F6-962F-FFD1-E905-9B8BAE05FD1E
treatment provided by	Felipe
scientific name	Leocrates bitungensis
status	sp. nov.

Treatment

Leocrates bitungensis , new species

( Figs. 2–4 View Fig View Fig View Fig )

Material examined. Holotype: 1 ( MZB. Pol. 00240), Lembeh Strait, Bitung City , North Sulawesi Province, 1°27′09.4″N, 125°14′22.7″E, coll. Joko Pamungkas, 14 December 2017. GoogleMaps

Description. Specimen complete with dorso-ventrally flattened body consisting of 16 chaetigers measuring 18 mm long by 3 mm wide at widest area, slightly tapering posteriorly from middle part of body. Body colour in alcohol shiny pale yellow with a more intense colouration on dorsum ( Fig. 2 View Fig ). Prostomium wider than long with anterior margin slightly wider than the posterior, width about half of anterior body width ( Figs. 2A View Fig & 3A View Fig ). Three antennae present. Lateral antennae with indistinct ceratophores, longer than prostomium (i.e., by nearly 1.4 times) and palps (i.e., by nearly 1.6 times). Median antenna much smaller and shorter, about half of prostomium length, situated between posterior eyes, right at body midline ( Figs. 2A View Fig & 3A View Fig ). Between two lateral antennae and symmetrically situated at body midline lies a large conical facial/frontal tubercle ( Figs. 2A View Fig & 3A View Fig ). Palps biarticulated with cylindrical palpophores and conical palpostyles; palpophores larger, 2.3 times longer than palpostyles ( Figs. 2A View Fig & 3A View Fig ). Two pairs of black round eyes present; anterior eyes twice as large and farther apart than posterior pair ( Figs. 2A View Fig & 3A View Fig ). Pharynx fully everted, muscular and slightly expanded distally, with about 30 lobes at anterior margin. Single mid-dorsal and mid-ventral conical jaws present. Dorsal jaw golden and larger; ventral jaw brown and smaller. Lateral vesicles absent ( Figs. 2A & B View Fig , 3A View Fig ). A pair of horizontal C-shaped nuchal organ lobes present, situated posterior to prostomium posterior margin, concealed by anterior margin of tentacular belt. Eight pairs of tentacular cirri with distinct cirrophores supported by visible jet-black acicula present, arranged in three rows, each with 3-3-2 pairs of cirri arranged in dorsal to ventral direction ( Figs. 2A View Fig & 3A View Fig ).

Both dorsum and ventrum with lateral cushions, situated at base of each parapodium, pale yellow in colour, size gradually increasing posteriorly up to chaetiger 11, then becoming smaller again towards the last chaetiger ( Figs. 2 View Fig & 3 View Fig ). A faint mid-dorsal longitudinal groove seen around middle part of body ( Fig. 2A View Fig ). Anterior end of ventrum muscular and V-shaped, followed posteriorly by a very shallow but wide longitudinal furrow measuring about half of body width (excluding lateral cushions and parapodia) starting from chaetiger 2 to posterior end. Transverse striae seen along body length, connecting parallel lateral cushions ( Fig. 2B View Fig ).

Dorsal cirri whip-like and much longer than ventral cirri; longest dorsal cirri at chaetigers 10 and 11, i.e., nearly 0.4 times body length ( Fig. 2A View Fig ). Length of ventral cirri almost similar in all chaetigers ( Fig. 2B View Fig ). Parapodia of chaetigers 1–4 uniramous with dorsal and ventral cirri ( Fig. 4A View Fig ). Parapodia of chaetigers 5–16 subbiramous, i.e., notopodia considerably smaller than neuropodia ( Fig. 4B & C View Fig ). Notoacicular lobes with a blunt tip bearing a jet-black aciculum ( Fig. 4B & C View Fig ). Notochaetae delicate and sparse ( Fig. 4B View Fig ). Neuroacicular lobes projected, with a blunt tip, wider than long ( Fig. 4B & C View Fig ). Neurochaetae compound falcigers with bidentate blades, guards approaching subdistal tooth ( Fig. 4D View Fig ); about 20 chaetae per bundle, blade length decreasing in size ventrally ( Fig. 4A–C View Fig ).

Posterior region tapered. Prepygidial segment with two pairs of dorsolateral cirri. Pygidium with a dorsoterminal anus bearing two paired anal cirri ( Figs. 2A View Fig & 3B View Fig ). Oocytes not seen.

Remarks. Leocrates bitungensis , new species, differs from all other Leocrates species in that its anterior eyes are small, i.e., approximately 1/15 of the prostomial width, and larger than the posterior ones. In addition, the distal end of the notoacicular lobes is blunt, and the number of neurochaetae are scarce, with about 20 chaetae per bundle. Based on these characteristics, L. bitungensis , new species, closely resembles L. reishi Salazar-Vallejo, 2020 . Leocrates bitungensis , new species, however, possesses: (1) lateral antennae with indistinct ceratophores, (2) a pharynx without lateral vesicles, (3) lateral cushions situated at the base of each parapodium, (4) projected neuroacicular lobes with a blunt tip that is wider than long, and (5) the body colour (in alcohol) that is shiny pale yellow with a more intense colouration on the dorsum. Leocrates reishi , by contrast, possesses: (1) lateral antennae with distinct ceratophores, (2) a pharynx with lateral vesicles, (3) lateral cushions situated between parapodia, (4) projected neuroacicular lobes with a blunt tip that is as long as wide, and (5) the body colour (in alcohol) that is shiny brownish with a more intense colouration on the dorsum.

Leocrates bitungensis , new species, is also similar to L. ahlfeldae Salazar-Vallejo, 2020 from India, L. chinensis Kinberg, 1866 from Hong Kong, and L. giardi Gravier, 1900 from the Red Sea. Nevertheless, L. bitungensis , new species, along with L. reishi , are the only species with blunt notoacicular lobes, whereas the other three species have tapered notoacicular lobes. A small number of neurochaetae (15–20 per bundle) in L. bitungensis , new species, also distinguishes this species from both L. ahlfeldae and L. chinensis . The number of neurochaetae in L. giardi is comparable to those in L. bitungensis , but in the former, the notoacicular lobes are tapered.