Sigambra grubii Mueller , 1858

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 grubii Mueller, 1858 Figs 3 , 4

Sigambra grubii Müller, 1858: 214-215, pl. 6, figs 7-9; Pettibone 1966: 182, fig. 13 a–c (reinstatement); Salazar-Vallejo 1990: 508-511, figs 1, 2, 4 A–C, table 1 (redescription, key to species); Hartwich 1993: 104 (1 syntype).

Sigambra grubei : Licher and Westheide 1997: 3 (new orthography).

Material examined.

Brazil. Pontal da Daniela (27°27'11"S, 48°31'47"W), in the Santa Catharina Island, Florianópolis. One specimen, 13RC1, July 2018 [mature female, anterior fragment (6.5 mm long, 0.9 mm wide, 54 chaetigers, first dorsal hooks from chaetiger 17)]. One specimen, S1R2, Feb. 2018 [anterior fragment (3.5 mm long, 0.5 mm wide, 27 chaetigers; first dorsal hooks from chaetiger 14)]. One specimen, S2R2C1, Feb. 2018 [anterior fragment (3.7 mm long, 0.8 mm wide, 26 chaetigers; first dorsal hooks from chaetiger 21)]. One specimen, S3R1C1, Feb. 2018 [postlarva (1 mm long, 0.2 mm wide, 13 chaetigers; first dorsal hooks from chaetiger 9)]. Four specimens for SEM (ECOSUR).

Description.

Prostomium blunt, two or three times wider than long ( Figs 3A, B , 4A, B ). Palpophores massive, palpostyles barely projected ( Fig. 4C ); interpalpal area distinct, anteriorly depressed, slightly expanded posteriorly. Antennae tapered, median one two or three times longer than laterals, laterals surpassing tips of palps, median antenna reaching chaetiger 6 or 7. Lateral antennal depressions indistinct.

Pharynx not exposed ( Fig. 4C ), with 14 thick, prismatic papillae, four lateral ones larger; tips indistinct. Basal pharynx apparently smooth.

Tentacular segment 4-5 times wider than long, with a single transverse row of globular tubercles, with two or three additional short middorsal series; dorsal tentacular cirri slightly longer than ventral ones, as long ( Fig. 4A ) or half as long ( Fig. 3A, B ) as dorsal cirri of chaetiger 1.

Parapodial cirri tapered throughout body. Dorsal cirri slightly expanded basally, longer than ventral ones. Ventral cirri as long as neurochaetal lobes in anterior and median chaetigers, longer in posterior ones, missing on chaetiger 2. Prechaetal lobes truncate, projected along its upper margin ( Fig. 3C ), postchaetal lobes long, acute. Anterior and median parapodia with hypertrophied gonopores, margin granulose ( Fig. 3C , arrow).

Notochaetae include dorsal hooks from chaetiger 9-21 (size related), barely exposed initially, handles progressively exposed, without accessory capillaries. Neurochaetae include two or three supracicular shorter wider pectinates ( Fig. 4F, G ), sometimes with tiny paired denticles along each main tooth, approximately five infra-acicular narrower pectinates ( Fig. 3D, E ), and abundant finely denticulate capillaries ( Fig. 3E ).

Posterior region tapered into a truncate cone ( Figs 3F , 4D ); last 4-7 chaetigers without hooks. Pygidium with two ventrolateral anal cirri, as long as last eight chaetigers.

Remarks.

As indicated in the key below, Sigambra grubii Müller, 1858 resembles S. hernandezi sp. nov. by having dorsal hooks without accessory capillaries. Their main differences are in the size of median antenna, and in the number of posterior chaetigers without hooks. In S. grubii the median antenna is medium-sized, reaching chaetiger 3 or 4, and there are 4-6 posterior chaetigers without hooks, whereas in S. hernandezi the median antenna is shorter, reaching chaetiger 2 or 3, and there are only two posterior hookless chaetigers. Another subtle difference is the relative size of papillae along body: which are larger in S. grubii compared to S. hernandezi .

Distribution.

The species was described from Florianópolis, southern Brazil, and although it has been reported from a wide bathymetric range along the Brazilian coast, further investigations of this material might show the species to be restricted to shallow water sediments. An interesting fact about Ilha do Desterro (type locality), former name for Florianópolis is the origin of the name. Florianópolis was meant to be a tribute to Marshal Floriano Peixoto, the second President (1891-1894) of the Republic of the United States of Brazil, by combining the first name with the Greek term polis, meaning city. Up to 1893, the city was called Nossa Senhora do Desterro (Our Lady of Banishment) or simply Desterro.

Figures

Figure 3. Sigambra grubii topotype, small specimen (ECOSUR SEM P 1) A anterior region, dorsal view B same, close-up of anterior end C right parapodium, median chaetiger, of larger specimen (6.5 mm long), anterior view (arrow points to gonopore) D same, pectinate chaetae E same, another parapodium, pectinate chaetae F same, posterior region, dorsal view (asterisk indicates last chaetiger with notohooks). Scale bars: 200 µm (A, F), 110 µm (B), 100 µm (C), 22 µm (D), 12 µm (E).

Figure 4. Sigambra grubii topotypes, large specimen (ECOSUR SEM P 1) A anterior region, dorsal view B same, close-up of anterior end C another specimen, anterior end, frontal view D same, posterior region (asterisk indicates last chaetiger with notohooks) E specimen in A, median chaetigers (arrow points enlarged chaetae) F pectinate chaetae G same, detail showing bipinnate denticulation. Scale bars:: 280 µm (A), 250 µm (B), 170 µm (C), 110 µm (D), 230 µm (E), 8 µm (F), 2 µm (G).