Four new Caribbean Sigambra species (Annelida, Pilargidae), and clarifications of three other Sigambra species

Abstract

Sigambra grubii Müller, 1858 has been reported from many different coastal environments in Brazil and the Grand Caribbean. However, more than one species was thought to be included under this species group name. After the study of several subtle and consistent differences in specimens fitting the description S. grubii, a new Grand Caribbean species is herein recognized and described as S. hernandezisp. nov. Further, the study of other Sigambra specimens prompted the examination of type specimens of S. bassi (Hartman, 1947), and of S. wassi Pettibone, 1966 to clarify some morphological features, and three other new species are recognized and newly described: S. diazisp. nov. and S. ligneroisp. nov. from the southeastern Caribbean (Venezuela), and S. olivaisp. nov. from the northwestern Caribbean (México). Morphological features are also clarified for S. grubii by comparison with specimens from the type locality, Florianópolis, Brazil, and with type specimens of S. bassi from Florida (U.S.A.), and non-type specimens of S. wassi from Virginia (USA). A key to identify all species of Sigambra is also included.

Description of the new species Sigambra nkossa (Annelida, Pilargidae), with an analysis of the distribution patterns of polychaetes associated with artificially hydrocarbon-enriched bottoms

“…This mixture of different populations, representing very likely different taxa, explain certainly the wide range of registered character variation, such as the starting of notopodial hooks between chaetigers 3–25 ( Licher & Westheide, 1997 ). This drawback was previously referred by other authors, and work is now under progress to solve it, likely implying erecting new taxa (see Salazar-Vallejo et al, 2019 and references therein). This fact led us to compare S. nkossa sp.…”

“…Remarks . Virtually all morphological features characterizing Sigambra have been well defined in recent literature ( Salazar-Vallejo et al, 2019 ; Glasby & Salazar-Vallejo, 2022 ). Our observations on the species found in the N’Kossa field, complemented with the original descriptions and figures of other species of the genus ( Table S6 ), lead us to suggest that the generic diagnosis probably requires to be amended in what concerns the so called “capillary chaetae” associated with the notopodial hooks/spines.…”

“…Sigambra. Müller (1858) : 214 (original description); Pettibone (1966) : 179 (genus reinstated with key to species); Licher & Westheide (1997) : 2 (key to species and synoptic table with characters of all species); Nishi et al (2007) : 65 (synoptic table with characters of all species); Salazar-Vallejo et al (2019) : 24 (diagnosis), 44–46 (key to species).…”

“…In the particular case of the presence of hooks, the starting chaetiger has been recently reported as being either invariable (or vary for a very few chaetigers, more or less at random) or as starting more posteriorly in larger specimens ( Salazar-Vallejo et al, 2019 ). Therefore, care should also be taken when attributing size-independence to a given character, as this may also vary significantly according to the species and along its ontogeny.…”