Nereis garwoodi Gonzalez-Escalante & Salazar-Vallejo, 2003

Conde-Vela, Victor M. & Salazar-Vallejo, Sergio I., 2015, Redescriptions of Nereisoligohalina (Rioja, 1946) and N. garwoodi Gonzalez-Escalante & Salazar-Vallejo, 2003 and description of N. confusa sp. n. (Annelida, Nereididae), ZooKeys 518, pp. 15-49 : 23-30

Taxon classification Animalia Phyllodocida Nereididae

Nereis garwoodi Gonzalez-Escalante & Salazar-Vallejo, 2003 Figures 3, 4, 6B, E, M, I, R

Nereis garwoodi González-Escalante and Salazar-Vallejo 2003: 156-160, figs 1 a–k, 2 a–h.

Type material.

Quintana Roo, Mexico. Lectotype ECOSUR 0065 and paralectotypes ECOSUR 0066 (7), Chetumal (18°29'38.88"N, 88°17'22.89"W), Chetumal Bay, 1 m depth, in calcareous sedimentary rocks, mixed bottom, September 24 1999, Coll. L.E. González-Escalante, S.I. Salazar-Vallejo.

Additional material.

Chetumal Bay, Quintana Roo, Mexico. ECOSUR P2829 (3), Alacranes (18°34'28.51"N, 88°14'24.21"W), May 1 1999, Coll. LEGE, SISV. ECOSUR P2830 (14), Chetumal, May 3 1999, Coll. LEGE, SISV. ECOSUR P2831 (29), Chetumal, 21 May 1999, Coll. LEGE, SISV. ECOSUR P2832 (17), Alacranes (18°34'28.51"N, 88°14'24.21"W), May 21 1999, Coll. LEGE, SISV. ECOSUR P2833 (2), Luis Echeverría (18°39'04 ’’ N 88°12'07 ’’ W), May 21 1999, Coll. LEGE, SISV. ECOSUR P2834 (28), Chetumal (18°29'38.88"N, 88°17'22.89"W), June 30 1999, Coll. LEGE, SISV. ECOSUR P2835 (9), Chetumal (18°29'38.88"N, 88°17'22.89"W), August 27 1999, Coll. LEGE, SISV.

Type locality.

Chetumal Bay, Mexico, Caribbean Sea, on rocks in mixed bottoms, 1 m depth.

Description.

Lectotype complete (ECOSUR 0065), atokous female, damaged with incisions at level of chaetigers 1, 15, and 30. Body tapering, 36 mm long, 1.7 mm wide, 95 chaetigers. Body pale, pigmentation faint, brown rectangle present dorsally on middle of anterior chaetigers, striated, discoloring toward end of body, lateral pale lines in anterior chaetigers only, oocytes present. Prostomium with brown pigment along inner margins of palps, two lines extending from antennae toward anterior pair of eyes separated by a longitudinal pale area, and two oval lateral patches; peristomium slightly pigmented, pale lines present (Fig. 3A).

Prostomium 1.5 times longer than wide; antenna cirriform, slightly passing palps; eyes subequal, black, in a rectangle (Fig. 3A). Peristomium twice longer than first chaetiger; tentacular cirri with short ceratophores, left cirri broken; dorsal longer than ventral ones, posterodorsal ones reaching chaetiger 12 (Fig. 3A).

Pharynx everted, jaws pale brown with 13 rounded teeth, extending to base (Fig. 3I). Maxillary ring: I = 15 pyramids in diamond, II = 31-31 pyramids and cones in arc, III = 44 cones in an ellipse, IV = 35-35 pyramids in arc (Fig. 3A). Oral ring: V = 1 cone, VI = 4-4 pyramids in diamond, VII-VIII = 42 in two irregular rows, P-bars alternating with small pyramids in anterior-most row, pyramids and cones with similar size alternating in posterior-most row.

Parapodial cirri pattern: Dorsal cirri longer than upper dorsal ligules throughout body; basally inserted on anterior region, displaced medially in midbody region, becomes subdistal in posterior chaetigers. Ventral cirri longer than neuropodial ligules in a few anterior chaetigers, progressively reduced throughout body; basally inserted on anterior region, barely migrating ventrally throughout body.

First two chaetigers uniramous, remaining ones biramous. In uniramous parapodia (Fig. 3D), dorsal cirri basal, slightly longer than notopodial ligules. Dorsal and neuropodial ventral ligules subequal, digitate, three times longer than neuroacicular ligules; neuroacicular ligules subconical, postchaetal lobes rounded. Ventral cirri subequal to neuropodial ventral ligules; both dorsal and ventral cirri with similar length and width.

In anterior parapodia (Fig. 3E), dorsal cirri medial, longer than notopodial ligules, extending beyond them. Notopodial dorsal ligules subconical, slightly longer than ventral ones; notopodial ventral ligules subconical, slightly longer than neuroacicular ligules, notoacicular papillae very conspicuous. Neuroacicular ligules subconical, subequal to ventral ones, postchaetal lobes rounded, slightly shorter than neuroacicular ligules; neuropodial ventral ligules digitate, basally attached to neuroacicular ligules. Ventral cirri shorter than neuropodial ventral ligules; dorsal cirri twice wider than ventral ones.

In middle parapodia (Fig. 3F), dorsal cirri medial, as long as notopodial ligules, extending beyond them. Notopodial dorsal and ventral ligules subequal, subconical, notoacicular papillae inconspicuous. Neuroacicular ligules subconical, slightly shorter than remaining ones, postchaetal lobes rounded, shorter than neuroacicular ligules; neuropodial ventral ligules digitate, basally attached to neuroacicular ones. Ventral cirri half as long as neuropodial ligule; both dorsal and ventral cirri with similar width.

In posterior parapodia (Figs 3G, H), dorsal cirri medial, slightly longer than notopodial ligule. Notopodial dorsal ligules become broad, longer than ventral ones; notopodial ventral ligules become large, 2-3 times longer than neuroacicular ligules, notoacicular papilla inconspicuous. Neuroacicular ligules subconical, half as long as neuropodial ventral ones, postchaetal lobes inconspicuous; neuropodial ventral ligules digitate, basally attached to neuroacicular ligules. Ventral cirri up to half as long as neuropodial ligule; dorsal and ventral cirri with similar width. Glandular masses conspicuous on notopodial ligules.

In anterior and midbody parapodia, notochaetae homogomph spinigers; neurochaetae homogomph spinigers and heterogomph falcigers in supra-acicular fascicles, heterogomph spinigers and falcigers in sub-acicular fascicles. In posterior parapodia, notochaetae homogomph spinigers and falcigers; neurochaetae as in anterior parapodia. Number of chaetae decreasing toward posterior end.

Notopodial homogomph spinigers pectinate, teeth decreasing in size distally (Fig. 3O). Notopodial homogomph falcigers with sigmoid blade, pectinate, distal tooth incurved, fused to blade (Fig. 3C). Neuropodial homogomph spinigers pectinate or basally serrate (Fig. 3J), heterogomph spinigers pectinate (Fig. 3P); both with teeth decreasing in size distally. Neuropodial heterogomph falcigers pectinate, distal tooth incurved, fused to blade, supra-acicular slightly broader than sub-acicular (Fig. 3 L–N); supra-acicular falcigers narrow in midbody chaetigers, becoming broad posteriorly (Fig. 3L, M).

Pygidium without modification; anal cirri cirriform, as long as last 4-5 segments (Fig. 3B).

Epitokes.

Paralectotype fully transformed male (ECOSUR 0066) complete, body tapering, 9 mm long, 1 mm wide, 46 chaetigers; paralectotype partially transformed female (ECOSUR 0066) incomplete, body tapering, 16 mm long, 2 mm wide, 63 chaetigers; fully transformed female (ECOSUR P0066) complete, body tapering, 12 mm long, 1.6 mm wide, 63 chaetigers. All with body yellowish with brown pigmentation present dorsally on first quarter of body, discoloring toward midbody chaetigers (Fig. 4E, F). Prostomium and peristomium with pigmentation similar to atokes (Fig. 4A, B).

Prostomium longer than wide; antennae cirriform, as long as palps; eyes black, subequal, in a rectangle, three times larger than antennal basal width (Fig. 4A, B). Peristomium twice length of first chaetiger; tentacular cirri with short ceratophores, dorsal tentacular cirri longer than ventral ones, posterodorsal reaching to chaetiger 9 in male, 13 in female (Fig. 4A, B).

Male with pharynx everted, jaws amber with 9 teeth. Maxillary ring: I = 6 pointed cones in triangle, II = 19-20 pointed cones in arc, III = 28 pointed cones in rectangle, IV = 22-19 pointed cones in arc. Oral ring: V = 1 pointed cone, VI = 4-3 pyramids in diamond, VII-VIII = 42 in two irregular rows, P-bars alternating with small pyramids in most-anterior row, pyramids alternating with cones with similar size in most-posterior.

Male body divided into two regions (Fig. 4E); pre-natatory region includes chaetigers 1-16, natatory region from chaetiger 17 to end of body. Fully transformed female body with two regions; pre-natatory includes chaetigers 1-26, natatory region from chaetiger 27 to end of body (Fig. 4F). Partially transformed female divided in two inconspicuous regions, lamellae start in chaetiger 25.

Parapodial cirri pattern: Anterior parapodia with dorsal cirri modified in chaetigers 1-7 in males, 1-5 in females; ventral cirri modified in chaetigers 1-5 in males, 1-4 in females. Dorsal cirri subequal to upper dorsal ligules in anterior chaetigers, become subequal throughout body; basally inserted in most-anterior region, displaced medially throughout body. Ventral cirri shorter than neuropodial ligules in unmodified chaetigers, subequal in modified region; basally inserted in anterior region, barely migrating ventrally throughout body.

Chaetigers 1-2 with uniramous (Fig. 4G, L), modified dorsal cirri basal, subpyriform in males, cattail-like in females, subequal to dorsal ligules. Dorsal and neuropodial ventral ligules subequal, subconical, twice longer than wide in male, 1.5 times longer than wide in female. Neuropodial lobe subconical, shorter than dorsal ligules; postchaetal lobes rounded. Modified ventral cirri shorter than neuropodial ventral ligules; dorsal and ventral cirri subequal with similar width and length.

Chaetigers 3-7 in males (Fig. 4H) and 3-5 in females (Fig. 4M) with slightly modified biramous parapodia. Modified dorsal cirri medial, cattail-like, slightly longer than notopodial ligules, extending beyond them; broader section as long as narrower one. Notopodial dorsal ligules subconical, slightly longer than notopodial ventral ligules; notopodial ventral ligules subconical, twice longer than neuroacicular ligules, notoacicular papillae conspicuous. Neuroacicular ligules subconical, postchaetal lobes rounded; neuropodial ventral ligules digitate, longer than neuroacicular ones. Modified ventral cirri cattail-like, subulate in chaetigers 6-7 in males and 5 in females, shorter than neuropodial ventral ligules.

Parapodial proportions as in atokous from chaetigers 8-16 in male and 6-26 in female (Fig. 4I, N).

Remaining parapodia modified (Fig. 4J, K, O, P). Dorsal cirri medial, subulate, ventral margins sinuate in males only, subequal to notopodial ventral ligules; basal lamellae large in males, small in females, increasing size toward posterior chaetigers and decreasing in most-posterior ones.

Notopodial dorsal ligules subconical, longer than ventral ones in male, subequal in female; notopodial ventral ligules subconical, developing a large ventral lamella in males only, with a round projection. Neuroacicular ligules subconical, shorter than notopodial ventral ones; postchaetal lobes developing into flabellate lamellae with a round projection in dorsal edge in males, small lamellae in females, progressively in creasing in size and decreasing in far posterior segments; neuropodial ventral ligules digitate, basally attached to neuroacicular ones. Ventral cirri subulate, slightly longer than neuroacicular ligules, with two basal lamellae of different sizes; dorsal cirri wider than ventral ones.

Prenatatory region with noto- and neurochaetae as in atokes, homogomph falcigers not observed. In natatory region, notochaetae and neurochaetae sesquigomph chaetae with finely serrated, paddle-like blades; atokous chaetae not completely replaced in specimens of either sex, homogomph falcigers observed in male (Fig. 4J, K, O, P).

Pygidium modified, anus surrounded by rosette of papillae in male, unmodified in female (Fig. 4C, D); anal cirri cirriform, as long as last 5-6 segments (Fig. 4C, D).

Variation.

The results of the analysis of body variation and analysis of paragnath numbers are summarized in Tables 1 and 2. The width measurements reported here differ from the original description because chaetiger width without parapodia was used, instead of measuring them including parapodia. The arrangement and number of paragnaths have similar ranges as those reported for Nereis oligohalina (Fig. 6B, E; Table 2); however, area I has a larger range, and the arrangement is somewhat variable, often in a triangle (Fig. 6I). Also, paragnaths are more robust than in Nereis oligohalina and Nereis confusa sp. n.

Regarding pigmentation, the striated rectangle seen in lectotype is more conspicuous in some specimens (Fig. 6M), which is also sometimes present in Nereis oligohalina , but the color is much more intense whereas the fingerprint-like pattern of the latter species was not observed. In mature specimens, the natatory region starts from chaetiger 17 only in males and 25-27 in females, which differs from the original description (22 in males and 21 in females). One specimen presented a duplicated ventral cirrus, but it was regarded as abnormal (Fig. 6R).

Remarks.

González-Escalante and Salazar-Vallejo (2003) indicated that they had six atokes and two epitokes as syntypes. Five atokous syntypes were expected to be sent to four foreign museums, but were never dispatched. Further, these syntypes were not formally deposited and labeled, and parts of the descriptions and illustrations are too imprecise to enable separation of Nereis garwoodi from Nereis oligohalina .

In an attempt to redefine the species, a lectotype has been selected ( ICZN 1999, Art. 74.1) to avoid future confusion; although the syntype series has better preserved specimens, the lectotype matches the original description and illustration, and was therefore preferred ( ICZN 1999, Recomm. 74B). In order to ensure their validity, the term has been introduced in the material section and in the description ( ICZN 1999, Art. 74.7.1, 74.7.3), and the lectotype has been described, illustrated and their data updated for its recognition ( ICZN 1999, Art. 74.7.2, Recomm. 74C, 74E); the remaining syntypes are regarded as paralectotypes ( ICZN 1999, Recomm. 74F). These specimens are deposited in ECOSUR.

Nereis garwoodi is closely allied with Nereis oligohalina , but they differ in some features in both atokous and epitokous forms, and in their habitats. In atokes, Nereis garwoodi never shows the dark brown coloration nor the fingerprint-like pattern found in Nereis oligohalina . The ranges of paragnath numbers of both species overlap and therefore are not useful to separate them, and the relative length of tentacular cirri would be useful if fixation method is the same (Table 1).

In Nereis garwoodi , both dorsal and neuropodial ventral ligules are twice as long as neuroacicular ligules in uniramous chaetigers, whereas in Nereis oligohalina these are subequal and slightly longer, respectively. Also, in Nereis garwoodi the neuropodial postchaetal lobes are visible in the anterior and midbody only, whereas in Nereis oligohalina they are visible throughout body.

Further, Nereis garwoodi has notopodial ventral ligules twice as long as neuropodial ventral ones in posterior chaetigers, whereas in Nereis oligohalina these ligules are subequal to each other; further, in Nereis oligohalina neuropodial ventral ligules are medially attached in posterior chaetigers, whereas in Nereis garwoodi they are basally attached throughout body. Moreover, in Nereis garwoodi notopodial homogomph falcigers have more teeth and they are narrower than in Nereis oligohalina ; also, in Nereis garwoodi the blades of supra-acicular heterogomph falcigers become broader and shorter in posterior chaetigers, but this modification is not present in Nereis oligohalina .

In epitokes, Nereis garwoodi has modified, cattail-like dorsal cirri present in biramous chaetigers with the basal sections as long as distal ones, whereas in Nereis oligohalina basal sections are longer. Also, in general Nereis garwoodi have better developed lamellae in natatory chaetigers than Nereis oligohalina , especially the basal lamellae of the dorsal cirri, the lamellae of both notopodial ventral and neuroacicular ligules. Moreover, epitokal transformation is more pronounced in females of Nereis garwoodi than in females of Nereis oligohalina . On the other hand, Nereis garwoodi is associated with calcareous rocks, while Nereis oligohalina is associated with reef-building bivalves and the mangrove Rhizophora mangle .

Habitat.

Chetumal Bay is a semi-closed, dynamic system linked to the Caribbean Sea by several freshwater tributaries, having a salinity gradient ranging 7-18 practical salinity units (psu) ( Carrillo et al. 2009). The species bores into calcareous sedimentary rocks, building mucous tubes, and has been regarded as a sedentary herbivore ( González-Escalante and Salazar-Vallejo 2003); to obtain the specimens, rocks must be broken. Although the Bay has extensive zones of mangroves, Nereis garwoodi has never been found among them.

Distribution.

Apparently restricted to Chetumal Bay. González-Escalante and Salazar-Vallejo (2003) report a gradient of decreasing abundance from the southern to the northern regions of the bay, probably related to organic matter load.