Pseudonereis citrina, 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 : 257-260

Pseudonereis citrina sp. n.

Figure 7

Pseudonereis gallapagensis Liñero-Arana & Reyes-Vásquez 1979: 8 –9, Pl. 7, Figs. 1–10 . Salazar-Vallejo & Jiménez-Cueto 1997: 369, Figs. 35, 36, 51 (non Kinberg, 1865).

Type material. Caribbean Sea, Mexico. Holotype ECOSUR 0 194, Mahahual , Quintana Roo (18°43'27.06"N 87°42'1.53"W), 19 January 2001, in corals, Coll. SI Salazar-Vallejo. Paratypes ECOSUR 0 195 (2), Akumal, Quintana Roo (20°23'38.41"N 87°18'55.61"W), 23 February 1986, Coll. M Aguilar, A Gómez . ECOSUR 0 196 (2), Xamach , Quintana Roo (19°55'36.85"N 87°26'9.17"W), 28 February 1986, Coll. M Aguilar, J Fernández .

Additional material. Caribbean Sea, Mexico. ECOSUR P1108 (1), Mahahual , Quintana Roo (18°43'27.06"N 87°42'1.53"W), 20 May 1997, Coll. SI Salazar-Vallejo, LF Carrera-Parra . ECOSUR P1222 (1), Playa Sol y Mar , Quintana Roo (18°46'36''N 87°40'14.4''W), 18 January 2000, Coll. SI Salazar-Vallejo, LF Carrera-Parra . ECOSUR P2278 (1), Vigía Chico , Quintana Roo (19°46'22.84"N 87°35'11.38"W), 27 February 1986, Coll. SI Salazar-Vallejo . ECOSUR P2932 (4), Puerto Morelos, Quintana Roo (20°50'52''N 86°52'29''W), 15 December 1986, Coll. P Gómez. Panama. USNM 73683 (2), Galeta Reef Flat, Canal zone, 1973, Coll. HO Brattstrom.

Type locality. Mahahual, Quintana Roo, Mexican Caribbean (18°43'27.06"N 87°42'1.53"W).

Etymology. The specific name stems from the Latin adjective citrinus, - a, - um, meaning lemon yellow, referring to the yellowish body and the presence of yellow glandular masses that are very conspicuous in the notopodial dorsal ligules of the posterior chaetigers.

Description. Holotype (ECOSUR 0194) complete, 19 mm long, 1.5 mm wide, 62 chaetigers, body damaged at chaetiger 30. One paratype (ECOSUR 0196) complete, 10 mm long, 0.8 mm wide at chaetiger 10, 51 chaetigers; another paratype (ECOSUR 0195) complete, 19 mm long, 3.9 mm wide at chaetiger 10, 70 chaetigers. Body pale, yellowish, translucent toward posterior end, tapered, pigments absent in all specimens.

Prostomium longer than wide; antennae lanceolate, half as long as prostomium, slightly passing the palps; eyes rounded, subequal, black, in trapezoidal arrangement ( Fig. 7A ). Achaetous ring 1.5 times longer than first chaetiger; anterior cirri with cirrophore conspicuous, longest cirri reaching chaetiger 5 ( Fig. 7A ).

Pharynx dissected; jaws brown, 13 teeth, distal end slightly incurved, cutting edge completely dentate ( Fig. 7C ). Maxillary ring: I= 3 cones in vertical line; II= 4–5 comb-like rows in triangle; III= 4 comb-like rows in triangle; IV= 4-4 comb-like rows and additional cones, merged cones and P-bars, in sigmoid. Oral ring: V= 0; VI= 1-1 shield-shaped bars with pointed ( Fig. 7D ) and blunt ( Fig. 7E ) tips; VII–VIII= one furrow row with 11 P-bars and one ridge row with 10 cones in a single band, rows vertically displaced; furrow and ridge regions with one paragnaths 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; subequal from anterior to posterior chaetigers, slightly shorter in posterior-most segments; basally inserted to neuropodial ventral ligules throughout body.

First two chaetigers with neuroaciculae only, remaining ones with both noto- and neuroaciculae; conspicuous glandular masses on tips of ligules and lobes throughout body. In first two chaetigers ( Fig. 7F ), dorsal cirrus basal, 1.5 times longer than dorsal ligule. Dorsal ligule digitiform, as long as neuropodial ventral ligule, slightly longer than neuroacicular ligule. Neuroacicular ligule digitiform, twice wider than long, distally bilobed, both superior and inferior lobes subequal, sometimes inconspicuous; postchaetal lobe rounded, as long as neuroacicular one; neuropodial ventral ligule digitate. Ventral cirrus basal, slightly longer than neuropodial ventral ligule.

In anterior and middle chaetigers ( Fig. 7G–H ), dorsal cirrus medial, 2–3 times longer than notopodial dorsal ligule. Notopodial dorsal ligule subconical, blunt, subequal than notopodial ventral ligule; notopodial ventral ligule subconical, blunt, shorter than neuroacicular ligule. Neuroacicular ligule subconical, twice wider than long, twice as long as neuropodial ventral ligule, distally bilobed, both superior and inferior lobes subequal, sometimes inconspicuous; postchaetal lobe rounded, as long as neuroacicular one; neuropodial ventral ligules digitiform. Ventral cirrus basal, subequal to neuropodial ventral ligule.

In posterior chaetigers ( Fig. 7I ), dorsal cirrus subdistal, 1.5 times longer than notopodial dorsal ligule. Notopodial dorsal ligule subconical, blunt, shorter than notopodial ventral ligule; notopodial ventral ligule subconical, blunt, subequal to neuroacicular ligule. Neuroacicular ligule subconical, blunt, twice wider than long, twice as long as neuropodial ventral ligule; postchaetal lobe inconspicuous; neuropodial ventral ligule digitiform. Ventral cirrus subulate, shorter than neuropodial ventral ligule.

In posterior-most chaetigers ( Fig. 7J ), dorsal cirrus distal. Notopodial dorsal ligule foliose, pennant-like, twice as long as wide, 1.6 times longer than dorsal cirrus, 5–6 times longer than notopodial ventral ligule; notopodial ventral ligule subconical, blunt, twice as long as neuroacicular ligule. Neuroacicular ligule subconical, blunt, 1.5 times wider than long, twice as long as neuropodial ventral ligule; postchaetal lobe inconspicuous; neuropodial ventral ligule digitiform. Ventral cirrus subulate, 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, coarse teeth, decreasing in size toward end ( Fig. 7O ). Neuropodial homogomph spinigers as notopodial ones; heterogomph spinigers serrate, basal teeth coarse, decreasing in size toward distal end ( Fig. 7K, P ). Neuropodial heterogomph falcigers falcate, pectinate, coarse teeth, half of inner edge edentate, distal tip stout; supra-acicular falcigers stouter than sub-acicular ones, falcigers become stouter toward posterior chaetigers ( Fig. 7L – N ).

Pygidium crenulated; anal cirri subulate, as long as last five chaetigers ( Fig. 7B ).

Variation. The results of the analysis of body variation and paragnaths number are summarized in Tables 1 and 2. W3 had the highest coefficient of correlation with TL, followed by nCh, W10, L10 and L3; RTC had no correlation with TL. Variation in paragnath number was very low, varying in one or two paragnaths in the areas I, V and 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. Pseudonereis citrina sp. n. resembles P. gallapagensis , but they have several differences. In P. citrina sp. n., the dorsal cirri are 2–3 times longer than notopodial dorsal ligules in anterior chaetigers, whereas in P. gallapagensis they are 1.2 times longer. Also, in P. citrina sp. n., notopodial dorsal ligules in posterior-most chaetigers are 1.6 times longer than dorsal cirri, whereas in P. gallapagensis they are 2.6 times longer. Furthermore, in P. citrina sp. n., the neuroacicular ligules are distally bilobate in anterior chaetigers only and sometimes they are no evident, whereas in P. gallapagensis they are distally bilobate throughout body. Finally, in P. citrina sp. n., teeth of neuropodial heterogomph falcigers are stouter and less numerous that in P. gallapagensis sp. n. P. citrina sp. n. resembles P. fauveli sp. n., mainly because the similar body size, the large dorsal cirri in anterior and middle chaetigers, and the translucent notopodial dorsal ligules in posterior chaetigers, but the former species can be readily recognized by having falcate dentate jaws, whereas P. fauveli sp. n. has helical edentate jaws; additional differences are discussed below.

The yellowish color of body in this species and the spotted notopodial dorsal ligules were observed in all material examined. The small size, the body color and enlarged dorsal cirri allow the easy recognition of this Caribbean species. The description of specimens as P. gallapagensis by Liñero-Arana & Reyes-Vásquez (1979) from Caribbean Venezuela matches with the current description of P. citrina sp. n., mainly in the parapodial proportions; Díaz-Díaz & Liñero-Arana (2002: 33) and Vanegas-Espinosa et al. (2007: 122), provided additional records of P. gallapagensis for Venezuela and argued that they are the same as described by Liñero-Arana & Reyes-Vásquez (1979), so likely they belong to P. citrina sp. n. as well. Record of P. variegata by Fauchald (1977a: 33) does not belong to P. citrina sp. n. nor P. brunnea sp. n. because the dorsal cirri are shorter than notopodial dorsal ligules in posterior chaetigers, whereas in the specimens described by Fauchald (1977a) both dorsal cirri and notopodial dorsal ligules are equal in length. Augener (1927: 48–49) recorded P. variegata from Curaçao based on epitokes and his specimens match P. citrina sp. n. in the terminal dorsal cirri of posterior-most chaetigers; however, because the epitoke morphology of P. citrina sp. n. is unknown, Augener’s record could represent another undescribed species.

Distribution. Caribbean Sea.

Figures

FIGURE 1. Proposal of division of pharyngeal midventral area. A, Kinberg’s drawings of ventral pharynx of Perinereis novaehollandiae (9C.) and Mastigonereis spinosa (10C.), showing the area VII and VIII as originally was intended; gray areas are intended to highlight midventral area in white. B, midventral area, composed of the areas III, VII and four subareas of area VIII; areas VII and VIII subdivided in furrow (lowercase letters) and ridge (uppercase letters) regions from both left (suffix l) and right (suffix r). A redrawn from Kinberg (1910).

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 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 7. Pseudonereis citrina sp. n. Holotype A–C, F–P (ECOSUR 0194); paratypes D (ECOSUR 0195) and E (ECOSUR 0196). A, anterior end, dorsal view. B, posterior end, dorsal view (insert: close-up of glandular masses in notopodial ligules). C, left jaw, dorsal view. D and E, pharynx areas V and VI. F, chaetiger 2, right parapodium. G, chaetiger 10, right parapodium. H, chaetiger 24, right parapodium. I, chaetiger 38, right parapodium. J, chaetiger 56, right parapodium. K, sub-acicular heterogomph spiniger, chaetiger 56. L, supra-acicular heterogomph falciger, chaetiger 56. M, sub-acicular heterogomph falciger, chaetiger 56. N, sub-acicular heterogomph falciger, chaetiger 38. O, notopodial homogomph spiniger, chaetiger 38. P, sub-acicular heterogomph spiniger, chaetiger 56. Scale bars: A, B, 1 mm; C, 0.3mm; D, E, 0.1 mm; F–J, 0.2 mm; K–N, 10 µm; O, P, 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.

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.

FIGURE 10. Pseudonereis variegata (Grube & Kröyer in Grube, 1858). Topotype A–B, I–J (USNM 176578); topotype C– H (USNM 176579). A, anterior end, dorsal view. B, posterior end, dorsal view. C, anterior end, dorsal view (insert: close-up of chaetigers 20–22). D, pharynx, dorsal view. E, same, ventral view. F, chaetiger 1, right parapodium. G, chaetiger 13, right parapodium. H, chaetiger 41, right parapodium. I, chaetiger 56, right parapodium. J, sub-acicular heterogomph falciger, chaetiger 56. Scale bars: A–C, 1 mm; D, E, 0.5 mm; F–I, 0.1 mm; J, 10 µm.