Sigambra olivai, Salazar-Vallejo, Sergio I., Rizzo, Alexandra E., Leon-Gonzalez, J. Angel de & Brauko, Kalina M., 2019

Salazar-Vallejo, Sergio I., Rizzo, Alexandra E., Leon-Gonzalez, J. Angel de & Brauko, Kalina M., 2019, Four new Caribbean Sigambra species (Annelida, Pilargidae), and clarifications of three other Sigambra species, ZooKeys 893, pp. 21-50 : 21

Sigambra olivai sp. nov. Figs 9 , 10

Type material.

Holotype (ECOSUR 219), Northwestern Caribbean, México, Nichupté Lagoon, NW sector, Halodule , Sta. 1 (21°08'55.60"N, 86°47'51.29"W), 1.5 m, 30 Oct 1987, M.S. Jiménez & J.J. Oliva, coll. Paratypes (9): One (ECOSUR 220), Nichupté Lagoon, NW sector, Halodule , Sta. 1 (21°08'55.60"N, 86°47'51.29"W), 1.5 m, 30 Oct 1987, M.S. Jiménez & J.J. Oliva, coll. One (ECOSUR 221), Nichupté Lagoon, NW sector, Halodule , Sta. 1 (21°08'55.60"N, 86°47'51.29"W), 1.5 m, 22 Apr. 1988, M.S. Jiménez & J.J. Oliva, coll. One (ECOSUR 222), Nichupté Lagoon, NE sector, Bojórquez Lagoon, Halodule , Sta. 2 (21°07'58.38"N, 86°45'10.39"W), 1.5 m, 27 Oct. 1987, M.S. Jiménez & J.J. Oliva, coll. One (ECOSUR 223), Nichupté Lagoon, NE sector, Bojórquez Lagoon, Halodule , Sta. 2 (21°07'58.38"N, 86°45'10.39"W), 1.5 m, 1 Feb. 1988, M.S. Jiménez & J.J. Oliva, coll. Two (ECOSUR 224), Nichupté Lagoon, NE sector, Bojórquez Lagoon, Halodule , Sta. 2 (21°07'58.38"N, 86°45'10.39"W), 1.5 m, 5 Jul. 1988, M.S. Jiménez & J.J. Oliva, coll. One (ECOSUR 225), Nichupté Lagoon, NE sector, Bojórquez Lagoon, Halodule , Sta. 2 (21°07'58.38"N, 86°45'10.39"W), 1.5 m, 5 Jul. 1988, M.S. Jiménez & J.J. Oliva, coll. Two (ECOSUR 226), Nichupté Lagoon, NE sector, Bojórquez Lagoon, Thalassia , Sta. 3 (21°07'01.24"N, 86°45'41.01"W), 1.5 m, 20 Abr. 1988, M.S. Jiménez & J.J. Oliva, coll.

Additional material.

Northwestern Caribbean, México. One specimen (ECOSUR), Nichupté Lagoon, NE sector, Bojórquez Lagoon, Thalassia , Sta. 3 (21°07'01.24"N, 86°45'41.01"W), 1.5 m, 29 Oct. 1987, M.S. Jiménez & J.J. Oliva, coll.

Diagnosis.

Sigambra with median antenna twice as long as laterals; chaetiger 2 without ventral cirri; dorsal cirri larger than ventral ones; dorsal hooks from chaetiger 30-39, without capillaries; posterior chaetigers without capillary notochaetae; pharynx with 13-16 marginal papillae.

Description.

Holotype (ECOSUR 219) twisted, broken into two pieces, larger fragment plus posterior end, some median parapodia with hypertrophied gonopores. Body contracted, cylindrical anteriorly, depressed medially and posteriorly, 20 mm long (anterior fragment 14 mm long, posterior one 6 mm long), 2.8 mm wide, 152 chaetigers (90 + 62). Dorsal integument rugose, areolate, especially after chaetigers 6-7 ( Figs 9A , 10A ). Parapodia removed from paratype.

Prostomium blunt, four times wider than long. Palps with palpophores massive, as long as wide, palpostyles blunt, short, with an oblique basal mark; interpalpal area distinct, blunt anteriorly, expanded posteriorly. Antennae tapered, median antenna twice as long as laterals (left lateral antenna broken), laterals surpassing tips of palps, median antenna reaching chaetiger 2 or 3. Lateral antennal depressions indistinct.

Pharynx with distal ring exposed ( Fig. 9A, B ), with 15 papillae of similar size, each conical with a globular mucron (rarely duplicated). Basal pharynx ring exposed in one paratype ( Fig. 10 A–C ), with 3-5 series of short, globular papillae, better visible laterally.

Tentacular segment eight or nine times wider than long; dorsal tentacular cirri slightly longer than ventral ones ( Figs 9B , 10B, C ), about half as long as dorsal cirri of chaetiger 1.

Parapodial cirri tapered throughout body. Dorsal cirri basally expanded, longer than ventral ones. Ventral cirri as long as neurochaetal lobes in anterior and median chaetigers, longer in posterior ones ( Fig. 10 D–F ), missing on chaetiger 2. Prechaetal lobes truncate, slightly projected along its upper margin, postchaetal lobes long, acute. Median parapodia with hypertrophied gonopores, showing distinct globular, papillate or smooth surfaces ( Fig. 10E , inset).

Notochaetae only dorsal hooks from chaetiger 38, barely exposed initially, more projected posteriorly, without accessory capillaries. Neurochaetae include two or three supracicular shorter wide pectinates, 4-5 infra-acicular narrow pectinates, especially along anterior and median segments, and abundant, long finely denticulate capillaries.

Posterior region tapered into a small blunt cone; last two chaetigers hookless. Pygidium with two ventrolateral anal cirri ( Fig. 9C ).

Oocytes inside parapodial spaces, ca. 100 µm in diameter.

Variation.

Complete specimens 15-24 mm long, 128-150 chaetigers. Antennae are easily eroded during sieving, but in undamaged specimens the median one is twice as long as lateral ones. Dorsal hooks start in chaetigers 30-39, apparently a size-dependent variation. There are no capillary chaetae with dorsal hooks in posterior chaetigers; last two have no hooks.

Etymology.

This species is named after José Juan Oliva-Rivera, amphipod taxonomist in ECOSUR, in recognition of his efforts sampling and processing benthic invertebrates from Nichupté Lagoon, Cancún, México. The specific epithet is a noun in the genitive case ( ICZN 1999, Art. 31.1.2).

Remarks.

Sigambra olivai sp. nov. resembles S. constricta (Southern, 1921) by having median antenna twice as long as the laterals, and dorsal hooks from chaetigers 30-40. They especially differ in the presence of a constriction on chaetiger 4, and of capillary notochaetae in posterior chaetigers. In S. olivai there is no constriction on chaetiger 4, and there are no capillaries in posterior chaetigers, whereas in S. constricta the body has a constriction on chaetiger 4, and there is a single capillary notochaetae in posterior chaetigers.

Distribution.

Only known from Nichupté Lagoon, Cancún, México, in seagrasses, mostly Halodule sp., in sediments of about 1 m depth.

Figures

Figure 9. Sigambra olivai sp. nov., holotype (ECOSUR 219), stained with Shirlastain-A A anterior region, dorsal view B anterior region, lateral view C posterior end, dorsal view, stained with Methyl green. Scale bars: 1.0 mm (A), 0.4 mm (B), 0.2 mm (C).

Figure 10. Sigambra olivai sp. nov., paratype (ECOSUR 221), stained with Shirlastain-A A anterior region, dorsal view B same, left, slightly oblique lateral view C same, anterior end, ventral view D another paratype (ECOSUR 226, complete), chaetiger 30, right parapodium, posterior view E same, chaetiger 35, right parapodium, posterior view; asterisk indicates the gonopore (insets: notohook and close-up of interramal gonopore) F same, chaetiger 90, right parapodium, anterior view (inset: notohook). Scale bars: 0.3 mm (A-C), 0.2 mm (D), 150 µm (E, F).