Laonice (Laonice) persica, Sikorski & Pavlova & Martin & Gil, 2023

Sikorski, Andrey, Pavlova, Lyudmila, Martin, Daniel & Gil, João, 2023, New sublittoral species of Laonice (Annelida: Spionidae) from southern Asian coasts, Zootaxa 5277 (3), pp. 490-508 : 492-494

Laonice (Laonice) persica sp. nov.

Figs 1A–H , 6 .

LSID: urn:lsid:zoobank.org:act:B598C9EF-4924-44C0-B42C-403558109C1C

Holotype. MNCN16.01 /19125, Persian Gulf , Iran, st. 19, 27°29.156′N, 52°34.003′E, 19 m depth, 34.9% of gravels (0.5‒10 mm), 5.8% of silt and clay (<63 µm), 17 June 1998.

Paratypes. MNCN16.01 /19126, 2 specimens, Persian Gulf , Iran, st. 8, 27°30.229′N, 52°33.574′E, 19 m depth, 45.1% of gravels (0.5‒10 mm), 7.8% of silt and clay (<63 µm), 17 June 1998 ; MNCN16.01 /19127, 1 specimen, Persian Gulf , Iran, st. 24, 27°28.797′N, 52°34.168′E, 18 m depth, 22.4% of gravels (0.5‒10 mm), 6.8% of silt and clay (<63 µm), 17 June 1998 .

Description. Body 0.4–0.5 mm wide (0.4 mm in holotype, one anterior fragment with 51 chaetigers and one short middle fragment with 18). Posterior region not collected.

Prostomium fused with peristomium at fronto-lateral margins ( Fig. 1A, G ), anteriorly rounded, posteriorly extending to chaetiger 23–26 (26 in holotype) as a low narrow caruncle. Nuchal organs as U-shaped ciliary bands on both sides of caruncle. Occipital antenna large (absent in paratypes, without traces of attachment). Two pairs of eyes in trapezoidal arrangement; median pair large, bean-shaped; lateral pair small, located ahead, set wider apart and often deeply embedded into tissue ( Fig. 1A ).

Branchiae from chaetiger 2 to 31–34 (32 in holotype), shorter than notopodial postchaetal lamellae at chaetiger 2; 1.5–2 times longer than notopodial postchaetal lamellae on following 15 chaetigers, more than twice longer at midbody (due to decreasing length of notopodial postchaetal lamellae) and shorter than notopodial postchaetal lamellae on last two branchiate chaetigers.

Notopodial postchaetal lamellae ear-like on anterior 25–30 chaetigers ( Fig. 1C–E ), narrowing upwardly, usually with acute tips on first four chaetigers, then tips becoming slightly rounded. Largest notopodial lamellae from chaetiger 4–10, with tips touching dorsally at chaetiger 4, significantly shortening along postbranchiate region, becoming rounded above and reduced below notochaetal fascicle/notopodium insertion level ( Fig. 1F ). Neuropodial postchaetal lamellae ear-like, almost triangular ( Fig. 1C–E ), largest on chaetigers 8–22, shortening afterwards, becoming very short and hardly detectable on postbranchiate chaetigers ( Fig. 1F ).

Dorsal transverse crests connecting notopodial postchaetal lamellae absent ( Fig. 1B ).

Lateral inter-neuropodial pouches starting from chaetiger 4–6 (5 in holotype), not visible after chaetiger 32–34.

Capillaries of anterior chaetigers arranged in two vertical rows. Neuropodial hooks from chaetiger 29–32, up to seven per neuropodium, with one pair of lateral small apical teeth and a single superior median tooth above main fang, appearing tridentate in lateral view ( Fig. 1H ). Notopodial hooks not seen. Sabre chaetae from chaetiger 17–22 (20 in holotype), one per fascicle.

Pygidium not seen, missing.

Pigmentation absent.

Methyl Green staining. Strong in upper parts of notopodial postchaetal lamellae from chaetiger 4 to 8–10 ( Fig. 1G ); very weak and diffuse on ventral surface of chaetigers 24–35, where it fades remarkably sooner than on notopodial postchaetal lamellae.

Type locality. Persian Gulf , Iran, northwest of Naband Gulf (27°29.156′N, 52°34.003′E), 19 m depth .

Etymology. The specific epithet persica derives from the toponymic name of the inlet where the types were collected, the Persian Gulf.

Distribution. Persian Gulf (Indian Ocean) ( Fig. 6 ).

Remarks. The existence of specimens having and lacking occipital antenna is not unique to L. persica sp. nov., having been also reported in the type-material of L. bahusiensis ( Sikorski et al. 2021b) .

Laonice persica sp. nov. has the prostomium completely fused with the peristomium, which places the species in L. ( Laonice ) as defined by Sikorski et al. (2017). It also lacks entire dorsal transverse crests connecting the notopodial postchaetal lamellae, and so belongs to the L. cirrata complex, together with L. brevicornis ( Kinberg, 1866) [including the junior synonyms L. aperata Radashevsky & Lana, 2009 and L. petersenae Radashevsky & Lana, 2009 ], L. quadridentata Blake & Kudenov, 1978 , L. bassensis Blake & Kudenov, 1978 (likely), L. shamrockensis Sikorski, 2003 , L. asaccata Sigvaldadóttir & Desbruyères, 2003 , L. pinnulata Radashevsky & Lana, 2009 , L. cricketae Sikorski & Pavlova, 2016 , and L. plumisetosa Bogantes et al., 2018 . However, L. cirrata is much larger (adults up to 5 mm wide), with hooks usually appearing bidentate in lateral view (tridentate in L. persica sp. nov.) and with lateral inter-neuropodial pouches appearing from chaetiger 52 (absent after chaetiger 32–34 in L. persica sp. nov.). Laonice brevicornis has tridentate hooks in lateral view and worms are not large (1.5–2 mm wide), but inter-neuropodial pouches are either absent or present only from chaetigers 3–17. Laonice cricketae has nuchal organs reaching chaetiger 20 and lateral inter-neuropodial pouches appearing only from chaetiger 40 (5–6 in L. persica sp. nov.), while the fusion of prostomium and peristomium is not so evident. Finally, L. shamrockensis , L. asaccata , L. pinnulata and L. plumisetosa have nuchal organs reaching chaetiger 5, 4, 7 and 1, respectively (23–26 in L. persica sp. nov.), while lateral inter-neuropodial pouches appear from chaetiger 3 in L. shamrockensis , L. pinnulata and L. plumisetosa and are absent in L. asaccata (5–6 in L. persica sp. nov.). Nuchal organ are also remarkably shorter in L. quadridentata (reaching chaetiger 18) and L. bassensis (reaching chaetiger 7).

Figures

FIGURE 1. Laonice persica sp. nov. A: anterior region (10 chaetigers), dorsal view. B: end of branchiate region (chaetigers 31–35), dorsal view. C–F: parapodia of chaetigers 7, 20, 32 and 46, frontal view. G: staining pattern with Methyl Green, anterior region (10 chaetigers), dorsal view. H: neuropodial hooded hook, lateral view. Scale, mm: A–F, 1; G, 1.4; H, 0.05. Material: A–B, G, paratype, Persian Gulf, st. 8 (MNCN16.01/19126); C–F, H, holotype, Persian Gulf, st. 19 (MNCN16.01/19125).

FIGURE 6. Location of the different species of Laonice discussed in the study: Persian Gulf (dot), Andaman Sea (square), Gulf of Siam (star), and Yellow Sea (triangle).