Pseudonereis fauveli, Conde-Vela, 2018

Conde-Vela, Víctor M., 2018, New species of Pseudonereis Kinberg, 1865 (Polychaeta: Nereididae) from the Atlantic Ocean, and a review of paragnath morphology and methodology, Zootaxa 4471 (2), pp. 245-278 : 260-264

Pseudonereis fauveli sp. n.

Figure 8

Pseudonereis ferox Fauvel 1914: 120 –123, Pl. 7, Figs. 13–17 (non Hansen, 1882).

Nereis (Perinereis) variegata Augener 1918: 205 –209 (non Grube & Kröyer in Grube, 1858).

Type material. Eastern Atlantic Ocean , Equatorial Guinea. Holotype USNM 1494007 , paratypes UMML 22.1128 (10) and paratypes ECOSUR 0 190 (4), R/ V Pillsbury, Cruise 6504, St. 271 (01°25'S 05°38'E), Annobón, 19 May 1965 . Paratypes UMML 22.1129 (2), R/ V Pillsbury, Cruise 6504, St. 273 (01°24'S 05°37'E), North Annobón, 1.8 m depth, 19 May 1965 .

Additional material. Eastern Atlantic Ocean , São Tomé and Príncipe. MNHN A106 (3), São João dos Angolares , São Tomé, Gulf of Guinea , 8 August 1906 .

Type locality. Annobón, Equatorial Guinea (01°25'S 05°38'E), Gulf of Guinea.

Etymology. This species is named after Pierre Fauvel, eminent French scientist, for his numerous contributions in polychaete taxonomy.

Description. Holotype (USNM 1494007) complete, 21 mm long, 1.8 mm wide at chaetiger 10, 78 chaetigers. Body pale, translucent toward posterior end, pigments absent.

Prostomium longer than wide; one antenna remaining, cirriform, half as long as prostomium, slightly passing the palps; eyes black, rounded, subequal, in rectangular arrangement, diameter as long as base of antenna ( Fig. 8A ). Achaetous ring 1.5 times longer than first chaetiger; four pairs of anterior cirri, cirrophores conspicuous, longest cirri reaching chaetiger 6 ( Fig. 8A ).

Pharynx dissected; jaws light brown, helical, cutting edge crenulated, edentate, distal end truncated, distal margins of jaws in opposition when pharynx invaginated ( Fig. 8H ). Maxillary ring: I= 2 in vertical line; II= 3-3 comb-like rows in triangle; III= 4 comb-like rows in triangle; IV= 5-5 comb-like rows and additional cones, merged cones and P-bars, in sigmoid. Oral ring: V= 1 cone; VI=1-1 shield-shaped bars with pointed tips; VII-VIII= one furrow row with 11 P-bars and one ridge row with 9 cones in a single band, rows vertically displaced; furrow and ridge regions with one paragnath each.

Parapodial cirri pattern. Dorsal cirri several times longer than notopodial dorsal ligules in anterior and middle body, largest in middle body, becoming shorter in posterior-most chaetigers; basally inserted to dorsal ligules in most-anterior segments, displaced medially in anterior and medial chaetigers, subdistal in posterior chaetigers, and distal in posterior-most ones. Ventral cirri longer than neuropodial ventral ligules in anterior-most chaetigers; shorter from anterior to posterior chaetigers; basally inserted to neuropodial ventral ligules throughout body.

First two chaetigers with neuroaciculae only, remaining ones with both noto- and neuroaciculae; yellowish glandular masses on notopodial dorsal ligules throughout body. In first two chaetigers ( Fig. 8C ), dorsal cirrus basal, 1–5 times longer than dorsal ligule. Dorsal ligule digitiform, 1.3 times longer than neuroacicular ligule. Neuroacicular ligule subconical, as long as wide, distally bilobed, superior lobe smaller than inferior one; postchaetal lobe subconical, blunt, as long as neuroacicular ligule; neuropodial ventral ligule digitiform, slightly shorter than neuroacicular ligule. Ventral cirrus basal, slightly longer than neuropodial ventral ligule.

In anterior and middle chaetigers ( Fig. 8D–E ), dorsal cirrus medial, twice times longer than notopodial dorsal ligule. Notopodial dorsal ligule subconical, blunt, as long as notopodial ventral ligule; notopodial ventral ligule subconical, blunt. Neuroacicular ligule subconical, wider than long, 2–3 times longer than neuropodial ventral ligule, distally bilobed, superior lobe much smaller than inferior one; postchaetal lobe rounded, as long as neuroacicular ligule; neuropodial ligule digitiform. Ventral cirrus basal, shorter than neuropodial ventral ligule.

In posterior chaetigers ( Fig. 8F ), dorsal cirrus subdistal, as long as notopodial dorsal ligule. Notopodial dorsal ligule, pennant-like, twice as long as notopodial ventral ligule; notopodial ventral ligule digitiform, twice as long as neuroacicular ligule. Neuroacicular ligule rounded, 2–3 times longer than neuropodial ventral ligule, distally bilobed, both superior and inferior lobes subequal; postchaetal lobe rounded, as long as neuroacicular ligule; neuropodial ventral ligule digitiform. Ventral cirrus basal, shorter than neuropodial ventral ligule.

In posterior-most chaetigers ( Fig. 8G ), dorsal cirrus distal. Notopodial dorsal ligule foliose, pennant-like, 1.5 times longer than wide, twice as long as dorsal cirrus, 4–5 times longer than notopodial ventral ligule; notopodial ventral ligule digitiform, twice as long as neuroacicular ligule. Neuroacicular ligule rounded, subequal than neuropodial ventral ligule; postchaetal lobe inconspicuous; neuropodial ventral ligule digitiform. Ventral cirrus basal, shorter than neuropodial ventral ligule.

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

Notopodial homogomph spinigers pectinate, minute teeth, decreasing toward distal end. Neuropodial homogomph spinigers as notopodial ones ( Fig. 8I ); heterogomph spinigers serrate, basal teeth coarse, decreasing in size toward distal end. Neuropodial heterogomph falcigers falcate, pectinate, narrow teeth, half of inner edge edentate, distal tip stout; supra-acicular falcigers stouter than sub-acicular ones, falcigers become stouter toward posterior chaetigers ( Fig. 8J–M ).

Pygidium bilobed; anal cirri cirriform, as long as last six chaetigers ( Fig. 8B ).

Variation. The results of the analysis of body variation and paragnath number are summarized in Tables 1 and 2. L10 and W3 had the highest coefficient of correlation with TL, followed by nCh, W10 and L3; RTC had no correlation with TL. Variation in paragnath number is very low, varying in one or two paragnaths in the areas VII– VIII. The number of paragnaths in the areas V, VI and VII–VII is similar to found in other Pseudonereis species ( Bakken 2007, Table 1).

Remarks. The shape and position of jaws in P. fauveli sp. n. is distinctive: only truncate ends are opposed, resembling the cutting edges of a diagonal plier. This character is unusual in Pseudonereis species and even among nereidids, where typically cutting edges are faced throughout their length. P. fauveli sp. n. is similar to P. citrina sp. n. but some differences are notable. In P. fauveli sp. n., the jaws are helical and edentate, whereas in P. citrina sp. n. they are falcate and dentate. Also, in P. fauveli sp. n., the dorsal cirri in anterior and middle chaetigers are up to twice as long as the notopodial dorsal ligules, whereas in P. citrina sp. n. they are 2–3 times longer. Moreover, in P. fauveli sp. n., notopodial dorsal ligules are 4–5 times longer than notopodial ventral ligules in posterior-most chaetigers, whereas in P. citrina sp. n. they are 5–6 times longer. In P. fauveli sp. n., notopodial dorsal ligules are 1.5 times longer than wide in the posterior-most chaetigers, whereas in P. citrina sp. n. they are twice as long as wide. Finally, in P. fauveli sp. n., the teeth of the neuropodial heterogomph falcigers are narrower and more numerous than in P. citrina sp. n.

P. fauveli sp. n. also differs from P. variegata in the arrangement of the areas VII–VIII of the paragnaths: a single band with two rows is present in P. fauveli sp. n. whereas two bands with two rows each is present in P. variegata ; also, in P. fauveli sp. n., dorsal cirri are distally inserted to notopodial dorsal ligules in posterior-most chaetigers, whereas in P. variegata they are subdistally inserted. P. fauveli sp. n. is more similar to with P. gallapagensis based on the one band with two rows present in the areas VII–VIII. However, they differ in the relative size of dorsal cirri in anterior chaetigers, twice as long as notopodial dorsal ligules in P. fauveli sp. n., and subequal in P. gallapagensis ; and the relative size of notopodial dorsal ligules in posterior-most chaetigers, 4–5 times longer than notopodial ventral ligules in P. fauveli sp. n., and 7–8 times longer in P. gallapagensis .

Fauvel (1914) identified some specimens (MNHN A106) from São João dos Angolares, São Tomé, Gulf of Guinea as P. ferox . He noted the similarity between P. ferox and P. gallapagensis , and based on Gravier (1909), he retained the former as a valid species, but he changed his mind later ( Fauvel 1932: 111) and synonymized P. ferox and P. variegata with P. gallapagensis . Augener (1918) identified his specimens from Gulf of Guinea as Nereis (Perinereis) variegata , including the synonymy of Nereis mendax Stimpson, 1856 , a South African species previously transferred to Perinereis by Willey (1904: 262). The original description by Stimpson (1856: 392) is short and no illustrations were provided, preventing a reliable identification. Willey (1904) identified his specimens from Cape of Good Hope, South Africa as P. mendax and included illustrations of the anterior end and parapodia, but no details about the identification were made; moreover, he synonymized Mastigonereis podocirra Schmarda, 1861 and Nereis (Nereilepas) stimpsoni Grube, 1866 (both species from Cape of Good Hope) with P. mendax , perhaps because he did not find differences among the genera Paranereis , Perinereis and Pseudonereis based on paragnaths in the areas VI, even after the examination of Kinberg’s types. This fact explains in part the current list of synonyms for P. variegata ( Read 2018) . Based on the illustrations, P. mendax sensu Willey (1904, Pl. 13, Fig. 13, Pl. 14, Figs. 3–6) differs from P. fauveli sp. n. mainly in the presence of crescent-shaped bars in the areas VI and the subdistal insertion of dorsal cirri in posterior chaetigers in P. mendax , instead of shield-shaped bars in the areas VI and dorsal cirri distally inserted in P. fauveli sp. n.; similarly, M. podocirra and N. stimpsoni have dorsal cirri subdistally inserted to notopodial dorsal ligules in posterior-most chaetigers, whereas in P. fauveli they are distally inserted ( Grube 1868, Pl. 2, Figs. 8d, 8e ; Schmarda 1861, text Figs. A, B). Future studies are needed to clarify the status of the above species.

Distribution. Gulf of Guinea.

Figures

FIGURE 3. Transversal distribution of paragnaths in the furrow and ridge regions. A, Alitta succinea (ECOSUR P2729), five rows in two bands. B, distances among rows in region A of A. succinea, showing the gap between the bands. C, Nereis garwoodi (ECOSUR P2831), two rows in two bands. D, distances among rows in region A of N. garwoodi, showing the gap between the bands. E, Hediste cf. diversicolor (USNM 58131), three rows in two bands. F, distances among rows in region B r of H. cf. diversicolor, showing the gap between the bands. G, Perinereis floridana (ECOSUR P1100), three rows in two bands. H, distances among rows in region A of P. floridana, showing the gap between the bands. I, Pseudonereis gallapagensis (USNM 24266), two rows and one band. J. Platynereis magalhaensis (ECOSUR P2935), two rows and one band.

FIGURE 4. Longitudinal distribution of paragnaths in the furrow and ridge regions. A, Neanthes cf. acuminata (ECOSUR P2936), showing the longitudinal alignment of paragnaths. B, same, diagram of the distribution of paragnaths in a pharynx fully everted. C, Nereis pelagica (ECOSUR P2840), showing the irregular distribution of paragnaths. D, same, diagram showing the paragnaths longitudinally aligned, paragnaths of the same color belong to the same longitudinal row. E, same, diagram showing longitudinal rows obtained when connecting the dots (paragnaths) of the same row.

FIGURE 5. Classification of some rectangular-base paragnaths. A, shield-shaped bars. B, crescent-shaped bars. C and D, pointed bars (P-bars). Drawings show the tip (dark brown) and base (light brown) of paragnaths, in both anterior and superior views; each drawing is accompanied with a picture of the same paragnath and at the same view. Green arrowheads point toward the anterior end of the body, showing the relative position of the paragnaths in relation to the pharynx axis. Blue vertical triangles point to the distal tip of the paragnaths; red triangles point the midpoint of the bases, and white dotted lines represent the bases’ altitude lines. A, D, Pseudonereis brunnea sp. n. (ECOSUR P2926); B, Perinereis floridana (ECOSUR P1100); C, Nereis garwoodi (ECOSUR P2831).

FIGURE 6. Pseudonereis brunnea sp. n. Holotype A–H (ECOSUR 0191); paratypes I–O (ECOSUR 0192). A, anterior end, dorsal view. B, posterior end, dorsal view. C, chaetiger 2, right parapodium. D, chaetiger 10, right parapodium. E, Chaetiger 26, right parapodium. F, chaetiger 46, right parapodium. G, chaetiger 65, right parapodium. H, close up of anterior end. I, maxillary ring, frontal view. J, oral ring, frontal view. K, supra-acicular heterogomph falciger, chaetiger 55. L, sub-acicular heterogomph falciger, chaetiger 55. M, sub-acicular heterogomph spiniger, chaetiger 55. N, notopodial homogomph spiniger, chaetiger 55. O, sub-acicular heterogomph spiniger, chaetiger 55. Black triangles= points used for length measurement. Scale bars: A, B, 1 mm; C–G, 0.2 mm; H–J, 0.5 mm; K–M, 10 µm; N, O, 30 µm.

FIGURE 8. Pseudonereis fauveli sp. n. Holotype A–M (USNM 1494007). A, anterior end, dorsal view. B, posterior end, dorsal view. C, chaetiger 2, right parapodium. D, chaetiger 13, right parapodium. E, chaetiger 32, right parapodium. F, chaetiger 50, right parapodium. G, chaetiger 67, right parapodium. H, right jaw in lateral (left) and dorsal (right) view. I, supraacicular homogomph spiniger, chaetiger 13. J, supra-acicular heterogomph falciger, chaetiger 13. K, sub-acicular heterogomph falciger, chaetiger 13. L, supra-acicular heterogomph falciger, chaetiger 67. M, sub-acicular heterogomph falciger, chaetiger 67. Scale bars: A, 1 mm; B–H, 0.2 mm; I–M, 10 µm.