Stenoninereis martini Wesenberg-Lund, 1958, restricted

Conde-Vela, Victor Manuel, 2019, Sinkhole and brackish water nereidid polychaetes: Revision of Stenoninereis Wesenberg-Lund, 1958 (Annelida), Subterranean Biology 30, pp. 95-115 : 98-101

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https://dx.doi.org/10.3897/subtbiol.30.36273

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scientific name

Stenoninereis martini Wesenberg-Lund, 1958, restricted
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Stenoninereis martini Wesenberg-Lund, 1958, restricted Figures 1G View Figure 1 , 2 View Figure 2 , 3 View Figure 3

Stenoninereis martini Wesenberg-Lund 1958: 9-12, figs 2, 3 View Figure 3 , 4 a–c. Pettibone 1971: 39-41, figs 23 a–n (partim).

Material examined.

Syntypes. CARIBBEAN SEA, NETHERLANDS ANTILLES • 2; Sint Maarten, Devil’s Hole; 26 Jul. 1955; P.W. Hummelinck leg.; 20x5x1.5 m, water almost clear and slightly greenish brown, 10900 mg Cl/l; USNM 29726.

Additional material.

CARIBBEAN SEA, PUERTO RICO • 21; Laguna Joyuda, off Inlet canal; 18°7'30"N, 67°10'0.12"W; 9 Oct. 1979; R. Castro leg.; mud and shells, host gastropods; USNM 61623.

Description.

Two syntypes ( USNM 29726) in poor condition, dissections previously performed ( Figs 2 D–E View Figure 2 ). One syntype posteriorly incomplete, some anterior parapodia previously dissected, 2.4 mm long, 0.4 mm wide at chaetiger 10, 16 chaetigers ( Fig. 2A View Figure 2 ). The other syntype in two portions, anterior end very damaged, 3.5 mm long, 0.3 mm wide, 21 chaetigers, some posterior chaetigers previously dissected ( Fig. 2A View Figure 2 ). Non-type material ( USNM 61623) complete, 5 mm long, 0.3 mm wide, 32 chaetigers ( Fig. 2B View Figure 2 ). All specimens pale, no pigmentation remaining.

Prostomium wider than long, anterior margin shallowly cleft ( Figs 1G View Figure 1 , 2C View Figure 2 ); antennae subulate, half as long as prostomium; eyes black, subequal, anterior eyes reniform, twice larger than posterior rounded eyes, anterior and posterior pairs slightly overlapped ( Figs 1G View Figure 1 , 2 B–C View Figure 2 ). Achaetous ring half as long as first chaetiger; four pairs of anterior cirri, longest one reaching chaetiger 8 ( Figs 1G View Figure 1 , 2 A–B View Figure 2 ).

Pharynx dissected; jaws light brown, translucent, 13 teeth ( Fig. 3J View Figure 3 ). Pharynx surface bare.

All chaetigers having both noto- and neuroaciculae; dorsal cirri cirrophores and notopodial dorsal ligules of anterior chaetigers ciliated. In first two chaetigers ( Fig. 3A View Figure 3 ), no topodia small, rounded lobe with notoaciculum. Neuroacicular ligule subconical, twice longer than ventral cirrus. Ventral cirrus subulate, cirrophore and cirrostyle indistinct.

In anterior chaetigers ( Figs 2D View Figure 2 , 3B View Figure 3 ), dorsal cirrus as long as chaetiger width, excluding parapodia; cirrophore 2-3 times longer than cirrostyle, 1.6-2.0 times longer than notopodial dorsal ligule, twice longer than notopodial ventral ligule. Notopodial dorsal ligule digitiform, basally attached to, and slightly shorter than, notopodial ventral ligule; notopodial ventral ligule subconical to digitiform, 2.8-3.0 times longer than wide, 1.0-1.3 times longer than neuroacicular ligule. Neuroacicular ligule subconical, 1.8-2.0 times longer than wide, 2.0-2.5 times longer than ventral cirrus. Ventral cirrus subulate, cirrophore and cirrostyle indistinct.

In middle chaetigers ( Figs 2E View Figure 2 , 3C View Figure 3 ), dorsal cirrus shorter than wide of chaetiger excluding parapodia; cirrophore 1.5 times longer than cirrostyle, 1.5 times longer than notopodial ventral ligule. Notopodial dorsal ligule absent in dissected syntype, digitiform in non-type specimen, 0.4 times as long as notopodial ventral ligule; notopodial ventral ligule subconical, 1.8-2.0 times longer than wide, as long as neuroacicular ligule. Neuroacicular ligule subconical, 1.4-1.8 times longer than wide, 1.7 times longer than ventral cirrus. Ventral cirrus subulate, cirrophore and cirrostyle indistinct.

In posterior chaetigers ( Figs 2F View Figure 2 , 3 D–E View Figure 3 ), dorsal cirrus shorter than chaetiger width, excluding parapodia; cirrophore 0.6 times as long as cirrostyle, half as long as notopodial ventral ligule. Notopodial dorsal ligule absent; notopodial ventral ligule subconical, 1.3-1.4 times longer than wide, half as long as neuroacicular ligule. Neuroacicular ligule subconical, 1.4-1.5 times longer than wide, 1.7 times longer than ventral cirrus. Ventral cirrus subulate, cirrophore and cirrostyle indistinct.

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

Notopodial and neuropodial supra-acicular sesquigomph spinigers with blade smooth ( Figs 3 F–G View Figure 3 ). Neuropodial heterogomph spinigers with blades basally serrate, coarse teeth, larger teeth longer than blade width, 2/3 of the blade edentate and subulate ( Fig. 3H View Figure 3 ). Neuropodial heterogomph falcigers with very long blades ( Fig. 3I View Figure 3 ), increasing their length from upper to lower positions in the same fascicle; falcigers with blades smooth ( Fig. 3I View Figure 3 ).

Pygidium with two anal plate-like lobes; anal cirri missing in types ( Fig. 2A View Figure 2 ), as long as last five chaetigers in a non-type specimen ( Fig. 2B View Figure 2 ).

Remarks.

The syntypes revised are damaged, but some parapodia in good conditions were dissected and examined. There are a few differences between the current description and the original one. The syntypes include about 25 specimens of a wide range of size, including juveniles having the larval eyes ("In young specimens there are 6 eyes arranged in two triangles of three each …”) ( Wesenberg-Lund 1958). Wesenberg-Lund (1958) noted that notopodial dorsal ligules disappear from chaetiger 26 in the specimen dissected, but there is no indication about the number of chaetigers of such specimen, likely being the largest one 6 mm long, and 34 chaetigers. In the specimens examined, the notopodial dorsal ligules disappear from anterior chaetigers (about chaetiger 12). Remaining parapodial features in the current redescription match the original description, and the redescription by Pettibone (1971). Pettibone (1971) described the notopodia of the first two chaetigers as having "slender notoaciculum with short, conical, basal cirrophore of dorsal cirrus; style short (sometimes missing)", and such dorsal cirrus was depicted in the anterior end and the second chaetiger draw ings ( Pettibone 1971, figs 23a and g, respectively). However, there are no dorsal cirri in first two chaetigers of the specimens of this and all other known species.

On the other hand, the holotype of S. tecolutlensis ( USNM 174870) was examined for comparison, and differences are evident between it and S. martini . In S. tecolutlensis , the prostomial margin is deeply cleft and a median groove is present, reaching the anterior pair of eyes, whereas in S. martini the cleft is shallow, and there is no median groove. In S. tecolutlensis , the dorsal cirrophores are 1.5 times longer than cirrostyles and as long as notopodial dorsal ligules in anterior chaetigers, whereas in S. martini cirrophores are 2-3 times longer than cirrostyles and twice longer than notopodial dorsal ligules. Further, in S. tecolutlensis the cirrophores are as long as notopodial dorsal ligules in middle chaetigers and as long as them in posterior chaetigers, whereas in S. martini cirrophores are twice longer than notopodial dorsal ligules in middle chaetigers and half as long as them in posterior chaetigers. Both species are similar in other respects. The differences with S. elisae sp. nov. and S. lackeyi comb. n. are discussed in the remarks for these species.

The record of S. martini for the Gulf of Mexico by de León-González and Solís-Weiss (1997) is also different. The authors described specimens with ‘trilobate’ notopodia’, i.e., with notopodial prechaetal lobes, a feature absent in all known species; also, the notopodial dorsal ligules are present throughout the body in specimens from the Gulf of Mexico, whereas in S. martini and other known species the notopodial dorsal ligules disappear in posterior chaetigers. Further, the cirrophores are several times longer than cirrostyles along the body in the specimens from the Gulf of Mexico (4 in anterior, 3.3 in middle, and 2.3 in posterior chaetigers), and shorter than cirrostyles in posterior chaetigers (0.5) in the syntypes of S. martini ; this development of the dorsal cirri resembles the one found in S. elisae sp. nov. Furthermore, the cirrostyle/notopodial ventral ligule ratios in the specimens of S. martini from the Gulf of Mexico are almost the same along the body (1.4-1.5), whereas in the syntypes of S. martini the ratio decreases toward posterior chaetigers. Finally, the neuropodial sub-acicular spinigers in specimens from the Gulf of Mexico have 2/3 of the blade dentate, whereas in the syntypes of S. martini only 1/3 is dentate. These differences make doubtful the conspecificity of the specimens from the Gulf of Mexico with specimens from the Caribbean Sea, so a further study is needed to clarify their status.