Pseudonereis gallapagensis Kinberg, 1865

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 : 264-266

Pseudonereis gallapagensis Kinberg, 1865

Figures 2B , 3I , 9A–K

Pseudonereis gallapagensis Kinberg 1865: 174 ; 1910: 52, Pl. 20, Figs. 3B, 3C, 3 C’, 3F10, 3G s, 3G u. Gravier 1909: 629 –633, Pl. 16, Figs. 15–20. Hartman 1948: 68 –69 (partim). Hartmann-Schröder 1962b: 432 –434. Bakken 2007: 157 –159 (partim).

Type locality. Indifatigable Island (Santa Cruz Island), Galapagos Islands, Ecuador.

Material examined. Eastern Pacific Ocean, Peru. USNM 24262 (7), Salaverry , 19 October 1926, Coll. WL Schmitt . USNM 24263 (1), Paita , 6 October 1926, Coll. WL Schmitt . Ecuador. USNM 24264 (2), Salinas , 14 September 1926, Coll. WL Schmitt . USNM 24265 (3), Salinas , Coll. WL Schmitt . Chile. USNM 33263 (12), Valparaiso, 10 February 1963, Coll. WL Klawe .

Description. Specimens used for description (USNM 24265) complete, in good conditions. Largest specimen 49 mm long, 2 mm wide at chaetiger 10, 82 chaetigers; another one complete, 39 mm long, 1.7 mm wide at chaetiger 10, 80 chaetigers. Body soft, translucent in mid body, pigmentation absent ( Fig. 9A–B ).

Prostomium as long as wide; antennae cirriform, half as long as prostomium, not passing the palps; eyes black, rounded, subequal, in rectangular arrangement ( Fig. 9A ). Achaetous ring as long as first chaetiger; four pairs of anterior cirri, cirrophores conspicuous, longest one reaching chaetiger 4 ( Fig. 9A ).

Pharynx everted; jaws dark brown, cutting edge dentate. Maxillary ring: I= 2 cones in vertical line; II= 3-3 comb-like rows in triangle; III= 4 comb-like rows in triangle; IV= 6-6 comb-like rows and additional cones, merged cones and P-bars, in sigmoid ( Figs. 2B , 9C–D ). Oral ring: V= 1 cone; VI=1-1 shield-shaped bars with pointed and blunt tips; VII–VIII= one furrow row with 12 P-bars and one ridge row with 9 cones in a single band, rows vertically displaced; furrow and ridge regions with one paragnath each ( Figs. 2B , 3I , 9C–D ).

Parapodial cirri pattern: Dorsal cirri longer than notopodial dorsal ligules in anterior region, becoming shorter toward posterior end; basally inserted to dorsal ligules in most anterior segments, displaced medially in medial segments, subdistal in posterior segments and distal in posterior ones, extending beyond notopodial dorsal ligules throughout body. Ventral cirri subequal and basally inserted to neuropodial ventral ligules throughout body.

First two chaetigers with neuroaciculae only, remaining ones with both noto- and neuroaciculae. In first two chaetigers ( Fig. 9H ), dorsal cirrus basal, 1.5 times longer than dorsal ligule. Dorsal ligule digitiform, 1.5 times longer than neuroacicular ligule. Neuroacicular ligule subconical, subequal than neuropodial ventral ligule, distally bilobed, superior lobe smaller than inferior one; postchaetal lobe subconical, blunt, half as long as neuroacicular ligule; neuropodial ventral ligule digitiform. Ventral cirrus basal, as long as neuropodial ventral ligule.

In anterior chaetigers ( Fig. 9I ), dorsal cirrus medial, 1.2 times longer than notopodial dorsal ligule. Notopodial dorsal ligule subconical, blunt, subequal than notopodial ventral ligule and neuroacicular ligule; notopodial ventral ligule rounded. Neuroacicular ligule subconical, twice as long as neuropodial ventral ligule, distally bilobed, superior lobe much smaller than inferior one; postchaetal lobe subconical, half as long as neuroacicular ligule; neuropodial ventral ligule digitiform. Ventral cirrus basal, as long as neuropodial ventral ligule.

In middle chaetigers ( Fig. 9J ), dorsal cirrus medial, as long as notopodial dorsal ligule. Notopodial dorsal ligule subconical, blunt, subequal than notopodial ventral ligule; notopodial ventral ligule digitiform, subequal than neuroacicular ligule. Neuroacicular ligule subconical, twice as long as neuropodial ventral ligule, distally bilobed, superior lobe smaller than inferior one; postchaetal lobe subconical, blunt, half as long as neuroacicular ligule; neuropodial ventral ligule digitiform. Ventral cirrus basal, as long as neuropodial ventral ligule.

In posterior chaetigers ( Fig. 9K ), dorsal cirrus distal. Notopodial dorsal ligule foliose, pennant-like, twice as long as wide, 2.6 times longer than dorsal cirrus, 7–8 times longer than notopodial ventral ligule; notopodial ventral ligule subconical, blunt, as long as neuroacicular ligule. Neuroacicular ligule subconical, as long as neuropodial ventral ligule, distally bilobed, superior lobes smaller than inferior one; postchaetal lobe subconical, blunt, subequal than neuroacicular ligule; neuropodial ventral ligule digitiform. Ventral cirrus basal, as long as neuropodial ventral ligule.

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

Neuropodial heterogomph falcigers falcate, pectinate, narrow teeth, half to two thirds of inner edge edentate, distal tip stout; blades of heterogomph falcigers in anterior chaetigers narrower than in posterior ones, supraacicular falciger stouter than sub-acicular ones ( Fig. 9F–G ).

Pygidium crenulated; anal cirri cirriform, as long as last five segments ( Fig. 9B ).

Remarks. The original description by Kinberg (1865) is short and focused on the head features; some illustrations of the anterior end, the pharynx, a parapodium from chaetiger 10, a spiniger and a falciger were added in another publication ( Kinberg 1910). The current description agrees with the mentioned features. Hartman (1948: 68–69) examined the type, but only detailed the distal attachment of dorsal cirri in posterior chaetigers and presence of spinigers and falcigers in neuropodia and made reference to previous redescriptions by Gravier (1909) from Peru, and by Fauvel (1914) from Gulf of Guinea. Day (1967: 331) synonymized P. gallapagensis with P. variegata based on specimens from South Africa. The specimens examined agree with the description by Gravier (1909), but the specimens and description from Gulf of Guinea by Fauvel (1914) match P. fauveli sp. n., and the description by Day (1967) matches Nereis mendax Stimpson, 1856 species group but not with P. gallapagensis (see Remarks section of P. fauveli sp. n.).

Bakken (2007) redescribed P. gallapagensis based on the type material of the species and type material of P. formosa Kinberg, 1865 , previously regarded as synonym by Hartman (1948: 68–69); both authors agreed that type material of P. gallapagensis is in poor conditions, and consequently Bakken (2007) illustrated the species with the type of P. formosa . Based on specimens herein described, P. gallapagensis has some morphological differences with P. formosa , and consequently they are regarded as a valid species (see Remarks section of P. formosa ). Also, P. gallapagensis have high resemblance with P. brunnea sp. n., differences between them are discussed above (see Remarks section of P. brunnea sp. n.).

Rozbaczylo & Bolados (1980: 219) studied 28 specimens identified as P. gallapagensis from Iquique, northern Chile, and including a short description, but there are some differences based on the current description. In specimens from Iquique, the area I has one paragnath, whereas the examined specimens have two paragnaths in the area I. Also, in specimens from Iquique, the areas VI have crescent-shaped bars, whereas the examined specimens have shield-shaped bars in such areas (but see Discussion). Furthermore, specimens from Iquique have ventral cirri longer than neuropodial ventral ligules at least until the third posterior of the body, whereas in the examined specimens they are shorter. Finally, in specimens from Iquique, neuropodial heterogomph spinigers in sub-acicular fascicles were not observed, whereas in the examined specimens they appear from the middle chaetigers. Therefore, specimens from Iquique likely belong to a different species than P. gallapagensis as currently defined.

Distribution. Ecuador, Peru, Chile.

Figures

FIGURE 2. The midventral pharynx area in some nereidid genera. A, midventral area in Alitta succinea (ECOSUR P2729). B, midventral area in Pseudonereis gallapagensis (USNM 24266). C, midventral area in Nereis garwoodi (ECOSUR P2831). D, midventral area in Perinereis floridana (ECOSUR P1100). E, midventral area in Hediste cf. diversicolor (USNM 58131). F, midventral area in Kainonereis polaris (USNM 55514). G, midventral area in Platynereis magalhaensis (ECOSUR P2935). A– B and E–F show pharynges fully everted; C–D show pharynges partially everted; G shows a pharynx dorsally dissected. The midventral area in all drawings is highlighted in white.

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 9. Pseudonereis gallapagensis Kinberg, 1865. Non-types A–B, E–K (USNM 24265), non-type C–D (USNM 24266). A, anterior end, dorsal view. B, posterior end, dorsal view. C, pharynx, dorsal view. D, same, ventral view. E, subacicular heterogomph falcigers, chaetiger 12. F, supra-acicular heterogomph falciger, chaetiger 40. G, sub-acicular heterogomph falciger, chaetiger 40. H, chaetiger 2, right parapodium. I, chaetiger 12, right parapodium. J, chaetiger 30, right parapodium. K, chaetiger 73, right parapodium. Scale bars: A–D, 1 mm; E–G, 10 µm; H–K, 0.2 mm.