Re-evaluation of the morphology of the monotypic genera Lycastonereis Rao, 1981 and Ganganereis Misra, 1999 (Annelida, Phyllodocida, Nereididae) Author Conde-Vela, Víctor M. text Zootaxa 2019 2019-03-18 4567 3 450 460 journal article 28344 10.11646/zootaxa.4567.3.2 6e80279e-4853-4c39-8ff2-f59c18084052 1175-5326 2599025 C3EBBF3C-7F69-4F94-8A55-4823616C5366 Lycastonereis indica Rao, 1981 Figures 1 ; 2 Lycastonereis indica Rao 1981 : 213 –215, Figs. 1 A–D. Misra 1999 : 159 –160, Figs. 11A–F, 12A–E. Material examined. Bay of Bengal, India . USNM 62013 (3), Vasishta Godavari Estuary , Andhra Pradesh , east coast, India , no date, Coll. D. Srinivasa Rao. Description. Three specimens, all incomplete, in good condition, two used for description. Largest specimen ( Figs. 1 B–C; 2A, D–J) 30 mm long, 1 mm wide at chaetiger 10, 76 chaetigers, pharynx everted and complete; second specimen ( Figs. 1A , 2 B–C) 18 mm long, 1.8 mm wide at chaetiger 10, 55 chaetigers, pharynx everted and complete but in bad conditions, tissue previously dissected. Pigmentation present in all specimens, consisting in brown irregular spots along body ( Fig. 2A ); prostomium with two longitudinal, central lines, extending from the anterior margin to middle of prostomium, some additional rounded spots at the base of the cirrophores ( Figs. 1A , 2B ); one row of irregular spots in the anterior dorsal margin of the achaetous ring ( Figs. 1A , 2B ); in chaetigers 1 to about 30, one central and two lateral rectangular spots in the dorsum of each chaetiger, becoming darker toward middle chaetigers and fading in posterior ones ( Fig. 2A ), and some additional dark brown lines present in anterior and middle chaetigers ( Fig. 2A ). Prostomium as long as wide, anterior margin entire ( Fig. 2B ); antennae cirriform, one-third as long as prostomial length, not surpassing the palps ( Figs. 1A , 2D ); eyes minute, black, in trapezoidal arrangement, posterior pair twice as large as than anterior pair ( Figs. 1A , 2B ). Achaetous ring twice as long as than first chaetiger ( Figs. 1A , 2B ); three pairs of anterior cirri, posterodorsal pair reaching chaetiger 1 ( Figs. 1A , 2B ). Pharynx everted ( Figs. 2 B–D); jaws dark brown, cutting edge with several minute, blunt teeth. Maxillary ring: I= 1 rounded papilla; II= 2-3 rounded papillae; III= 3 papillae in row; IV= 1-1 papilla ( Figs. 2 C–D). Oral ring: V= 0; VI= 3-4 rounded papillae; VII-VIII= one ridge row with a series of five rounded papillae, ridge regions with one papilla each ( Figs. 2 C–D). First two chaetigers with neuroaciculae only, remaining ones with both noto- and neuroaciculae; neuropodial ventral ligules absent throughout body. In first two chaetigers ( Fig. 2G ), dorsal cirri subconical, as long as dorsal ligules. Dorsal ligules digitiform to subconical, as long as postchaetal lobes. Neuroacicular ligules bilobed, superior lobe digitiform, inferior lobe rounded and twice as wide as superior one; postchaetal lobes rounded, shorter than neuroacicular ligules. Ventral cirri digitiform, as long as postchaetal lobes. In anterior chaetigers ( Figs. 1B, D ; 2H ), dorsal cirri subconical, as long as notopodial dorsal ligules. Notopodial dorsal ligules subconical to digitiform, as long as notopodial ventral ligules; prechaetal lobes small, subconical; notopodial ventral ligules digitiform, half as long as neuroacicular ligules in anteriormost chaetigers, becoming as long as neuroacicular ligules toward mid body. Neuroacicular ligules bilobed, diminishing in size toward mid body, superior lobe digitiform, inferior lobe rounded; postchaetal lobes rounded, shorter than neuroacicular ligules. Ventral cirri digitiform, half as long as neuroacicular ligules. In middle chaetigers ( Fig. 2I ), dorsal cirri subconical, as long as notopodial dorsal ligules. Notopodial dorsal ligules digitiform, as long as notopodial ventral ligules; prechaetal lobes small, subconical; notopodial ventral ligules digitiform, as long as neuroacicular ligules. Neuroacicular ligules unilobated, reduced, superior lobe rounded, inferior lobe inconspicuous; postchaetal lobe rounded, as long as neuroacicular ligules. Ventral cirri digitiform, half as long as neuroacicular ligules. In posterior chaetigers ( Figs. 1C , 2J ), dorsal cirri subconical, half as long as notopodial ventral ligule. Notopodial ventral ligules subconical, slightly shorter than neuroacicular ligules. Neuroacicular ligules subconical. Ventral cirri subconical, one-third as long as neuroacicular ligules. FIGURE 1. Morphology of Lycastonereis Rao, 1981 species. Non-type specimens A–D (USNM 62013). A , anterior end, dorsal view. B , chaetiger 10, right parapodium. C , chaetiger 41, right parapodium. D , diagrammatic view of chaetiger 3, right parapodium, distal view. Scale bars: A, 0.5 mm; B–D, 0.1 mm. Abbreviations: AdC, anterodorsal cirrus; An, antennae; AvC, anteroventral cirrus; Dc, dorsal cirrus; InL, inferior lobe (neuroacicular ligule); NaL, neuroacicular ligule; NoD, notopodial dorsal ligule; NoV, notopodial ventral ligule; PdC, posterodorsal cirrus; PoL, neuropodial postchaetal lobe; Pp, palpophores; Pr, prostomium; PreL, prechaetal lobe; Ps, palpostyle; SpL, superior lobe (neuroacicular ligule); Vc, ventral cirrus. Notochaetae homogomph spinigers. Neurochaetae homogomph spinigers and falcigers in supra-acicular fascicles, homogomph and sesquigomph spinigers and homogomph falcigers in sub-acicular ones. Notopodial and neuropodial supra-acicular homogomph spinigers pectinate, teeth minute, decreasing in size distally. Neuropodial sub-acicular sesquigomph spinigers pectinate, teeth minute, decreasing in size distally. Neuropodial sub-acicular homogomph spinigers pectinate, long and narrow teeth, basal teeth 3–4 times longer than blade width, slightly decreasing in size distally ( Fig. 2F ). Supra- and sub-acicular homogomph falcigers with inner margin edentate, blade medially broader ( Fig. 2E ). Posterior end missing. Remarks. The parapodial and chaetal features of the current specimens agree with the redescription of Lycastonereis indica by Misra (1999) , therefore they are regarded as conspecifics. The main difference between the current specimens and both the original description and redescription is the presence of papillae in both maxillary and oral ring. Rao (1981: 215) described the first segment (i.e. the anterior ring) as apodous, and all parapodia biramous thereafter, implying that the parapodia from the first and second chaetigers are as the remaining ones, whereas usually these first two chaetigers lack some notopodial processes and the notoaciculae; unfortunately, these parapodia were not depicted. Misra (1999) described the first two chaetigers as ‘uniramous’, i.e., lacking notoaciculae, which is confirmed here. Also, Rao (1981) mentioned the presence of heterogomph falcigers with ‘oar-shaped’ blades in the neuropodia, but his figure 1D shows a homogomph articulation, whereas Misra (1999) described homogomph falcigers in both supra- and sub-acicular fascicles, and here Misra’s observation is confirmed. The examined specimens lack posterior ends, but Misra (1999) described the pygidium as narrow, with two short anal cirri; the original specimens also lack posterior ends ( Rao 1981 ), and Misra (1999) noted that posterior ends usually are lost in specimens. FIGURE 2. Lycastonereis indica Rao, 1981 . Non-type specimens A–J (USNM 62013). A , anterior end, dorsal view. B , anterior end, dorsal view. C , pharynx, dorsal view (An: antennae; Roman numerals represent pharyngeal areas). D , anterior end, lateral view (Roman numerals represent pharyngeal areas). E , sub-acicular sesquigomph falciger, chaetiger 41. F , subacicular homogomph spiniger, chaetiger 41. G , chaetiger 1, right parapodium. H , chaetiger 3, right parapodium (neuropodial ventral ligule overlapped). I , chaetiger 18, right parapodium. J , chaetiger 41, right parapodium. Scale bars: A–B, 1 mm; C–D, 0.2 mm; E–F, 10 µm; G–J, 0.1 mm. Another difference is that it is the neuroacicular ligules which are distally bilobed, not the postchaetal lobes as Misra (1999) stated. Likely, the author overlooked the bundles of chaetae surrounding the inferior and superior lobes, which are clearly seen when parapodia are observed directly in the specimens, but not in mounted parapodia. In order to clarify this feature, a figure showing a distal view of an anterior parapodium is included ( Fig. 1D ). The neuropodial sub-acicular homogomph spinigers with long teeth were not depicted in the original description or redescription. The length of the teeth is unusual among nereidids; for example, Stenoninereis species have subacicular heterogomph spinigers with long basal teeth that diminishes their size distally (de León-González & Solís- Weiss 1997, Figs. 1D , 2E ), but those teeth are much coarser than in L. indica .