Labrorostratus Saint Joseph 1888

• Main Authors: Hernández-Alcántara, Pablo, Cruz-Pérez, Ismael Narciso, Solís-Weiss, Vivianne
• Format: Text
• Language: unknown
• Published: Zenodo 2015
• Subjects: Biodiversity; Taxonomy; Animalia; Annelida; Polychaeta; Eunicida; Oenonidae; Labrorostratus; San Martín; Pablo; Anvil; Pomona; Solís; North Atlantic
• Online Access: https://dx.doi.org/10.5281/zenodo.5627923; https://zenodo.org/record/5627923

Genus Labrorostratus Saint Joseph, 1888 Type species Labrorostratus parasiticus Saint Joseph, 1888 Diagnosis (emended). Prostomium without antennae, with four eyes along posterior margin. Peristomium with two apodous rings. One or two pairs of small maxillary plates, sometimes reduced to one pair of broad plates without teeth, or absent. One pair of long maxillary carriers, partially or completely fused, sometimes with an additional unpaired one. Mandibles well developed, wing-shaped, narrowly joined along median line. Parapodia uni- or sub-biramous. Chaetae simple, geniculate with smooth margin; simple modified ventral chaetae present or absent. Acicular spines absent. Pygidium rounded, with up to four small anal cirri. Remarks. Taxonomic difficulties for the identification of oenonids are usually attributed to the scarcity of external characters, so that the maxillary apparatus is essential to differentiate taxa (Steiner & Amaral 2009). The maxillae show different degrees of reduction in seven parasitic oenonid genera, but all previously known parasitic species have maxillary plates (Table 1). Up to now, only Biborin , a free-living taxon from California, was known to lack a maxillary apparatus (Chamberlin 1919). However, the reduction of maxillae is not rare among parasitic oenonids. Oligognathus benelliae and Pholadiphila turnerae , parasites found in echiurids and mollusks respectively, and the only oenonids found inside non-polychaete hosts, have three pairs of maxillae, which also occur in Oligognathus parasiticus Cerruti, 1909, a spionid parasite. In other taxa, such as Haematocleptes and Drilognathus , the maxillary apparatus is even more reduced (Table 1). In Haematocleptes , the maxillary carriers are often fused as one solid rod, but bearing a pair of small pieces free from the carriers (Hartman & Fauchald 1971), while in Drilognathus , a monospecific genus recorded from South Africa, the maxillary plates are absent and maxillary supports are reduced to a black cuticular ridge (Table 1). In Labrorostratus , the seven species described, including the species from the Caribbean, are mostly endoparasites of other polychaetes (syllids, nereidids and trichobranchids) (Table 2). Labrorostratus jonicus has been collected as free-living among algae, but it may have come out from a syllid after sampling or further handling (Tenerelli 1961). These endoparasitic relationships are associated with an evident reduction of the maxillary apparatus, but the main characteristic of Labrorostratus’ species are the wide variability in their jaw shapes: L. jonicus , L. luteus , L. parasiticus and Labrorostratus sp. San Martín & Sardá, 1986, have two pairs of maxillary pieces, while L. prolificus Amaral, 1977 has only one pair of maxillae with no teeth. That is why the presence of a jaw apparatus represented only by an elongate rod-like maxillary carrier as found in the Caribbean’s species is not surprising. This, together with the fact that Labrorostratus is the only genus of a parasitic Oenonidae bearing simple modified ventral chaetae, made it possible to assign the new species to this genus. However, it was also necessary to emend the diagnosis of the genus, to include species without maxillary plates; this emendation is based on a previous ones by Steiner & Amaral (2009) adding our own observations. Species Maxillae Mandibles Eyes Simplemodified Shape of chaetae Acicular spines Acicula Number of ventral chaetae projecting neuroacicula from lobe Drilognathus capensis Day, Black cuticular ridge, Wing shaped Two Absent Chaetae absent Absent Occasionally 1 1960 reminiscent of the long maxillary supports; no distinct maxillary plates Labrorostratus jonicus Two pairs of very small pieces. I: Two subtriangular Four Present Limbate Absent Absent 1 Tenerelli, 1961 small with 3 teeth; II: same plates with 2 rounded teeth along inner margins Labrorostratus luteus Two pairs of long, slender. I: Two subtriangular Four Present Limbate Absent Absent 1 Uebelacker, 1978 large, anvil-shaped; II: minute plates with outer with 4 teeth edges smooth ……continued on the next page Species Maxillae Mandibles Eyes Simplemodified Shape of chaetae Acicular spines Acicula Number of ventral chaetae projecting neuroacicula from lobe Labrorostratus parasiticus Two pairs of very small pieces. I: Two small curved Four Absent Limbate smooth Absent Absent 3 Saint Joseph, 1888 small with 4 teeth; II: same plates with outer edges smooth Labrorostratus prolificus A pair without teeth or spines, Two subtriangular Four Absent Limbate Absent Absent 2 Amaral, 1977 with very long stems attached all plates the way Labrorostratus sp. San Martín Two pairs of very small denticled Two subtriangular Four Absent Limbate Absent Absent 2 Sardá, 1986 (maybe L. pieces. I: 2 teeth; II: same plates parasiticus fide Martin & Britayev, 1998) Labrorostratus zaragozensis Two pairs of very small denticled Two subtriangular Absent Absent Limbate Absent Absent 2 Hernández-Alcántara & Solís- pieces. I: a distal tooth and 5 plates Weiss, 1998 small teeth; II: a large tooth, 2 distal teeth, 4 middle denticles Notocirrus? spinifera (Moore, Incompletely developed, with Wing shaped Four Absent Limbate serrated Absent Present 1 1906) (young) elongated rod-like maxillary carriers and developing denticled maxillae Oligognathus bonelliae Three pairs, each recurved and U-shaped, with two Four Absent Limbate serrated Absent Absent 1-2 Spengel, 1882 unidentate wing-like pieces of rods united by transverse band Oligognathus parasiticus Three pairs, each recurved and U-shaped, with two Absent Absent Limbate smooth Absent Absent 1 Cerruti, 1909 unidentate wing-like pieces of rods united by transverse band Pholadiphila turnerae Dean, Three pairs of equal maxillae Two large plates, Absent Absent Capillary hirsute Present Absent 1 1992 smooth, shield-like, spinosus united medially ......continued on the next page Species Host Number of parasites by Locality/depth Citations host : Published as part of Hernández-Alcántara, Pablo, Cruz-Pérez, Ismael Narciso & Solís-Weiss, Vivianne, 2015, Labrorostratus caribensis, a new oenonid polychaete from the Grand Caribbean living in the body cavity of a nereidid, with emendation of the genus, pp. 127-139 in Zootaxa 4048 (1) on pages 128-132, DOI: 10.11646/zootaxa.4048.1.8, http://zenodo.org/record/242519 : {"references": ["Saint Joseph, A. A. de (1888) Les Annelides polychetes des cotes de Dinard, pt. 2. Annales des Sciences Naturelles, Paris, 5, 141 - 338.", "Steiner, T. M. & Amaral, A. C. Z. (2009) Arabella aracaensis, a new species with growth rings on its mandibles, and some remarks on the endoparasitic Labrorostratus prolificus (Polychaeta: Oenonidae) from southeast Brazil. Journal of Natural History, 43, 2537 - 2551. http: // dx. doi. org / 10.1080 / 00222930903219988", "Chamberlin, R. V. (1919) New polychaetous annelids from Laguna Beach, California. Pomona College Journal of Entomology and Zoology, 11 (1), 1 - 23.", "Cerruti, A. (1909) Oligognathus parasiticus, n. sp. endoparassita dello Spio mecznikowianus Clpd. Archivio Zoologico, Napoli, 4 (2), 197 - 209.", "Hartman, O. & Fauchald, K. (1971) Deep-water benthic annelids off New England to Bermuda and other North Atlantic areas. Part II. Allan Hancock Monographs, Marine Biology, 6, 1 - 327.", "Tenerelli, V. 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Oceanography and Marine Biology: an Annual Review, 36, 217 - 340.", "Spengel, J. W. (1882) Oligognathus bonelliae, eine schmarotzende Eunicee. Mitteilungen aus der Zoologischen Station zu Neapel, 3, 15 - 52."]}