Paraleonnates sootai ( Misra, 1999 ) Conde-Vela, 2019

Conde-Vela, Víctor M., 2019, Re-evaluation of the morphology of the monotypic genera Lycastonereis Rao, 1981 and Ganganereis Misra, 1999 (Annelida, Phyllodocida, Nereididae), Zootaxa 4567 (3), pp. 450-460 : 455-457

Paraleonnates sootai ( Misra, 1999) n. comb.

Figure 3

Ganganereis sootai Misra 1999: 157 –159, Figs. 9A–H, 10A–F.

Type locality. Jhingakhali , Sundarbans, West Bengal, India .

Description (after Misra 1999). Anterior margin of prostomium deeply cleft ( Figs. 3 A–B); antennae cirriform, as long as prostomium ( Fig. 3A ); one pair of palps; two pairs of eyes, anterior pair reniform, posterior one rounded ( Figs. 3 A–B). Achaetous ring shorter than following segments; four pairs of anterior cirri, posteroventral pair reaching chaetiger 17 (14–18) ( Fig. 3A ). Pharynx with dentated jaws ( Figs. 3 B–C), 13 (13–14) teeth. Maxillary ring with 2–3 transversal rows of partly, distally sclerotized papillae on both dorsal and ventral surfaces of maxillary ring ( Figs. 3 B–C). Oral ring: V= 0; VI= two large soft papillae; VII-VIII= two rows of soft papillae, anterior row with 6 (4–6) papillae and posterior row with 7 (7–8) papillae ( Figs. 3 B–C). All chaetigers with both noto- and neuroaciculae. Dorsal cirri cirriform, twice as long as notopodial ventral ligules throughout body ( Figs. 3 D–G). Notopodial dorsal and ventral ligules subconical, subequal in anterior chaetigers ( Figs. 3 E–F), diminishing in size toward posterior end, notopodial dorsal ligules becoming a small lobe in posterior-most chaetigers ( Fig. 3F ), notopodial ventral ligules shorter than neuroacicular ligules throughout body ( Figs. 3 D–G); postchaetal lobes inconspicuous ( Figs. 3 D–G). Neuroacicular ligules bilobed, both superior and inferior lobes digitiform, subequal, reduced greatly in size toward posterior end ( Figs. 3 D–G); postchaetal lobe subconical with a digitiform tip and half as long as inferior lobes in anterior chaetigers, diminishing in size toward posterior end, inconspicuous in posterior-most chaetigers ( Figs. 3 D–G); neuropodial ventral ligules digitiform and as long as postchaetal lobes in anterior chaetigers, becoming a small lobe in posterior-most chaetigers ( Figs. 3 D–G). Ventral cirri cirriform, half as long as neuroacicular ligules in anterior chaetigers, becoming much shorter in posterior-most chaetigers ( Figs. 3 E–G). Notochaetae homogomph spinigers, some with narrow blades and minute teeth, others with broader blades and coarse teeth ( Fig. 3H ). Neurochaetae homogomph and sesquigomph spinigers in supraacicular fascicles, and sesquigomph and heterogomph spinigers in sub-acicular fascicles; homogomph spinigers similar to notopodial ones; some heterogomph spinigers with narrow blades and minute teeth, others with broader blades and coarse teeth ( Fig. 3I ); short-bladed sesquigomph spinigers with coarse ( Fig. 3J ) or minute teeth. Anal cirri as long as last 4 chaetigers.

Remarks. The detailed description and illustrations by Misra (1999) show that the morphological features of this species closely resemble Paraleonnates species, and agree with the current diagnosis of the genus ( Hong et al. 2012). The transference of Ganganereis sootai to Paraleonnates and the synonymy of Ganganereis with Paraleonnates is justified based on the similarities in pharyngeal, parapodial and chaetal features between genera. A key of Paraleonnates species is provided below, distinguishing P. sootai n. comb. from the other two described species, P. uschakovi Khlebovich & Wu, 1962 and P. bolus ( Hutchings & Reid, 1991) .

There are some differences between Paraleonnates sootai n. comb. and P. uschakovi and P. bolus ( Misra et al. 1987; Hutchings & Reid 1991; Qiu & Qian 2000; Hong et al. 2012;). In P. uschakovi and P. bolus , the dorsal cirri are longer than the notopodial dorsal ligules in anterior chaetigers and becoming shorter toward the posterior end, but in P. sootai n. comb. they are longer than notopodial dorsal ligules throughout body. In P. uschakovi and P. bolus , the notopodial dorsal ligules are subconical in anterior parapodia and become flattened and expanded in middle and posterior parapodia, whereas in P. sootai n. comb. they are subconical throughout the body. Moreover, in P. uschakovi there are 4 papillae in the posterior row in areas VII-VIII, whereas P. sootai n. comb. has 7–8 papillae; in P. bolus this feature is uncertain because Hutchings & Reid (1991: 58) mentioned two rows of papillae in the oral ring, whereas Qiu & Qian (2000: 1142) and Hong et al. (2012: 59) described a single row in the areas VII-VIII. Based on available descriptions, it seems that the sharply-pointed papillae of the anterior row fall in furrow regions, whereas the blunt papillae of the posterior row fall in ridge regions.

The small lobes above the dorsal cirri in P. uschakovi are very conspicuous in posterior parapodia (chaetigers 71 and 100), slightly visible in anterior-most ones (chaetiger 3), and inconspicuous in some anterior chaetigers (chaetiger 29) ( Hong et al. 2012, Figs. 5C–D, E–F, I–L). This pattern in anterior and middle chaetigers is shown in P. sootai n. comb., although the presence of well-developed lobes above dorsal cirri in posterior chaetigers was not depicted by Misra (1999). The reduction of notopodial dorsal ligules and neuropodial ventral ligules in posterior chaetigers ( Fig. 3F ), present in P. sootai n. comb. was also observed in P. uschakovi by Wu et al. (1985, Figs. 41G– H).

In the three species, well-defined bundles of neurochaetae were recognized. In P. uschakovi and P. bolus , there are three main kinds of bundles: 1) bundles with heterogomph, short-bladed spinigers in both supra- and subpreacicular fascicles; 2) bundles with homogomph and sesquigomph long-bladed spinigers in supra-postacicular fascicles; and 3) bundles with heterogomph long-bladed spinigers in sub-postacicular fascicles. In P. sootai n. comb., there are three kind of bundles: 1) bundles with sesquigomph spinigers in both supra- and sub-preacicular fascicles, 2) bundles with homogomph spinigers in supra-postacicular fascicles, and 3) bundles with heterogomph spinigers in sub-postacicular fascicles; the length of the blades in each bundle was not clearly stated, but likely the arrangement is similar to that found in the other two species, i.e., short-blades in preacicular fascicles and longblades in postacicular ones.

Figures

FIGURE 3. Paraleonnates sootai (Misra, 1999) n. comb. A, anterior end, dorsal view. B, pharynx, dorsal view. C, pharynx, ventral view. D, chaetiger 2, left parapodium, anterior view. E, chaetiger 5, left parapodium, anterior view. F, chaetiger 5, right parapodium, posterior view. G, chaetiger 120, left parapodium, anterior view. H, notopodial homogomph spiniger. I, subacicular heterogomph spiniger. J, supra-acicular sesquigomph spiniger. Scale bars: A–C, 1 mm; D–G, 0.25 mm; H–J, 10 µm. (Redrawn from Misra 1999, Figs. 9 and 10; A, D–J from holotype, B–C from paratype). Abbreviations: Dc, dorsal cirrus; InL, inferior lobe (neuroacicular ligule); LDc, lobe above dorsal cirrus; Mr, maxillary ring; NeV, neuropodial ventral ligule; NoD, notopodial dorsal ligule; NoV, notopodial ventral ligule; Or, oral ring; PoL, neuropodial postchaetal lobe; SpL, superior lobe (neuroacicular ligule); Vc, ventral cirrus.