Stenoninereis elisae, Conde-Vela, Victor Manuel, 2019

Conde-Vela, Victor Manuel, 2019, Sinkhole and brackish water nereidid polychaetes: Revision of Stenoninereis Wesenberg-Lund, 1958 (Annelida), Subterranean Biology 30, pp. 95-115 : 105-107

Stenoninereis elisae sp. nov. Figures 1 B–F, I ; 6

Type material.

Syntypes. CARIBBEAN SEA, PUERTO RICO • 5; Rio Grande, Espiritu Santo River, 50 m below Castanon confluent; Apr. 1977; W.R. Bhajan leg.; USNM 55366.

Additional material.

CARIBBEAN SEA, PUERTO RICO • 3; Rio Grande, Espiritu Santo River, 50 m above Castanon confluent; W.R. Bhajan leg.; USNM 55360.

Type locality.

Espiritu Santo River, Rio Grande, Puerto Rico.

Description.

Five syntypes ( USNM 55366) complete, in good condition. Specimen dissected complete, 62 mm long, 0.4 m wide at chaetiger 10, 27 chaetigers. All specimens pale ( Figs 6 A–B ).

Prostomium wider than long, anterior margin shallowly cleft ( Figs 1I , 6C ); antennae subulate, half as long as prostomium; eyes black, anterior and posterior eyes rounded, anterior eyes smaller than posterior ones, strongly overlapped, forming a pyriform spot ( Figs 1I , 6 A–C ). Achaetous ring as long as first chaetiger; four pairs of anterior cirri, longest one reaching chaetiger 6, anterodorsal pair lanceolate, remaining ones subulate ( Figs 1I , 6 A–C ).

Pharynx dissected; jaws brown, translucent, 8 teeth. Pharynx surface bare.

All chaetigers with noto- and neuroaciculae; dorsal cirri cirrophores and notopodial dorsal ligules of anterior chaetigers with ciliate surface. In first two chaetigers, notopodium with a small, rounded lobe bearing notoaciculum. Neuroacicular ligule subconical, twice longer than ventral cirrus. Ventral cirrus subulate, cirrophore and cirrostyle indistinct.

In anterior chaetigers ( Figs 6E ), dorsal cirrus longer than chaetiger width, excluding parapodia; cirrophore 5.5-6.0 times longer than cirrostyle, 2.6 times longer than notopodial dorsal ligule, 3 times longer than notopodial ventral ligule. Notopodial dorsal ligule digitiform, basally attached to, and 1.2 times longer than, notopodial ventral ligule; notopodial ventral ligule subconical, 2.3 times longer than wide, 1.3 times longer than neuroacicular ligule. Neuroacicular ligule subconical, 1.5 times longer than wide, 2.2 times longer than ventral cirrus. Ventral cirrus subulate, cirrophore and cirrostyle indistinct.

In middle chaetigers ( Figs 6 F–G ), dorsal cirrus longer than chaetiger width, excluding parapodia; cirrophore 2.5-3 times longer than cirrostyle, twice longer than notopodial dorsal ligule and becoming shorter toward posterior chaetigers, twice longer than notopodial ventral ligule. Notopodial dorsal ligule digitiform, as long as notopodial ventral ligule, rapidly decreasing in size toward posterior chaetigers and disappearing from chaetiger 23-25; notopodial ventral ligule subconical, twice longer than wide, 1.6 times longer than neuroacicular ligule. Neuroacicular ligule subconical, 1.2-1.4 times longer than wide, twice longer than ventral cirrus. Ventral cirrus subulate, cirrophore and cirrostyle indistinct.

In posterior chaetigers ( Fig. 6H ), dorsal cirrus as long as chaetiger width, excluding parapodia; cirrophore 1.4 times longer than cirrostyle, 1.5 times longer than notopodial ventral ligule. Notopodial dorsal ligule absent; notopodial ventral ligule subconical, twice longer than wide, as long as neuroacicular ligule. Neuroacicular ligule subconical, 1.3 times longer than wide, 1.3 times longer than ventral cirrus. Ventral cirrus subulate, cirrophore and cirrostyle indistinct.

Notochaetae sesquigomph spinigers. Neurochaetae sesquigomph spinigers in supra-acicular fascicles, heterogomph spinigers and falcigers in sub-acicular fascicles.

Notopodial ( Figs 1C , 6M ) and neuropodial ( Fig. 1D ) supra-acicular sesquigomph spinigers pectinate, very minute teeth, disappearing toward distal end. Neuropodial heterogomph spinigers ( Figs 1E , 6I ) serrate, coarse teeth, larger teeth longer than blade width, 1/3 of blade edentate, subulate. Neuropodial heterogomph falcigers ( Fig. 1F ) with very long blades, blades increasing their length toward posterior chaetigers, blades with basal and medial teeth minute, often inconspicuous ( Figs 6 J–L ), rarely some small teeth basally and distally ( Fig. 1E ); supra-acicular blades shorter than sub-acicular ones, blades of sub-acicular falcigers increasing their length from upper to lower positions in the same fascicle ( Figs 6 J–L ).

Pygidium with two anal plate-like lobes; anal cirri as long as last five chaetigers ( Fig. 6D ).

Etymology.

The name is after the late Dr. Elise Wesenberg-Lund, in recognition of her many works in polychaete taxonomy, especially freshwater ones, and by proposing the genus Stenoninereis . The name is a noun in apposition and was formed by the elision of the last vowel for euphony.

Remarks.

Due to the morphological variability observed in specimens belonging to Stenoninereis , the designation of syntypes was preferred (ICZN 1999, Art. 72.3). Stenoninereis elisae sp. nov. is easily recognized by the enlarged dorsal cirri in anterior and middle chaetigers, being two or three times longer than the width of their respective segments, and by the size and proximity of the eyes resulting into a pyriform shape. The cirrophore/cirrostyle lengths ratio is also distinctive for this species because the cirrophore is longer than cirrostyle throughout the body, whereas in S. lackeyi comb. n., S. martini , and S. tecolutlensis , cirrostyles are longer than cirrophores in posterior chaetigers. Also, the cirrophore/cirrostyle lengths ratios in S. elisae sp. nov. are greater than in the other species, especially in anterior (5.5-6.0) and middle (2.5-3.0) chaetigers. Finally, the blades of the neuropodial heterogomph falcigers are denticulated, whereas in the remaining species they are smooth.

The notopodial dorsal ligules exhibit a high variation in their length as shown in the cirrophore/ notopodial dorsal and notopodial ventral ligules/notopodial dorsal ligules ratios in anterior (2.3-7.1 and 1.3-3.4, respectively) and middle (1.3-3.8 in both ratios) chaetigers. This variability in the size of the notopodial dorsal ligules was also observed in specimens of S. lackeyi comb. n., and S. martini , but the ratios are less variable.

Figures

Figure 1. Morphology of Stenoninereis species A non-type of S. lackeyi comb. n. (USNM 53273) B, I syntypes of S. elisae sp. nov. (USNM 55366) C-F non-type of S. elisae sp. nov. (USNM 55360) G non-type of S. martini Wesenberg-Lund 1958 (USNM 61623) H holotype of S. tecolutlensis de Leon-Gonzalez & Solis-Weiss, 1997 (USNM 174870) A anterior end, dorsal view B chaetiger 6, left parapodium (solid and dashed red lines: vessels; solid and dashed light blue lines: unknown structures, likely nerves) C shaft of notopodial sesquigomph spinigers, chaetiger 20 D shaft of neuropodial supra-acicular sesquigomph spiniger, same chaetiger E shaft of neuropodial sub-acicular heterogomph spiniger, chaetiger 20 F Shaft of neuropodial sub-acicular heterogomph falciger, chaetiger 20 G-I anterior ends, dorsal view. Abbreviations: AC, anterior cirri; An, antennae; Cp, cirrophore; Cs, cirrostyle; DC, dorsal cirrus; Es, esophagus; NeL, neuroacicular ligule; NoD, notopodial dorsal ligule; NoV, notopodial ventral ligule; Ph, pharynx; Pp, palpophore; Ps, palpostyle; VC, ventral cirrus; ¿?, unknown structures, likely nerves by their position. Scale bars: 0.2 mm (A, G-I); 0.1 mm (B); 5 µm (C-F).

Figure 6. Stenoninereis elisae sp. nov. A-M Syntypes (USNM 55366) A whole specimen, dorsal view B whole specimens, dorsal view C anterior end, dorsal view D Posterior end, dorsal view E chaetiger 6, right parapodium, anterior view F chaetiger 16, right parapodium, anterior view G chaetiger 18, right parapodium, anterior view H chaetiger 24, right parapodium, anterior view I subacicular heterogomph spinigers, chaetiger 18 J-L subacicular heterogomph falcigers, chaetiger 18 M notopodial homogomph spiniger, chaetiger 49. Scale bars: 0.5 mm (A-B); 0.25 mm (C); 0.2 mm (E-H); 10 µm (I-L); 30 µm (M).