Brasilochondria riograndensis gen. nov., sp. nov. (Copepoda, Chondracanthidae) a parasite of flounders of Rio Grande do Sul State, Brazil

Br asilochondria riogr andensis gen. nov ., sp. nov acanthidae) Brasilochondria riograndensis nov., nov.. (Copepoda, Chondr Chondracanthidae) a par asite of fflounder lounder ande do Sul State, Br azil 1 lounderss of Rio Gr Grande Brazil parasite Vernon E. Thatcher 2 & Joaber Pereira Júnior 3 1 Contribuição número 1508 do Departamento de Zoologia, Universidade Federal do Paraná. 2 Departamento de Zoologia, Universidade Federal do Paraná. Caixa Postal 19020, 81531-980 Curitiba, Paraná, Brasil.Research Fellow of the CNPq. 3 Departamento de Ciências Morfobiológicos, Fundação Universidade Federal do Rio Grande, Rio Grande do Sul, 96200-050 Rio Grande, Rio Grande do Sul, Brasil. E-mail: ABSTRACT. Brasilochondria riograndensis gen. nov nov.. , sp. nov nov.. (Copepoda, Chondracanthidae) a parasite of the flounder, Paralichthys orbignyanus (Valenciennes, 1839), is described. The new genus has a spherical head a post-mandibular “neck” and two pairs of modified biramous legs. In these respects, it resembles Argentinochondria patagonensis Etchegoin, Timi & Sardella, 2003. In the Argentine genus, however, the bulbous head has a medial constriction and the posterior of the female lacks the lateral extensions that are present in the new genus. Pseudolernentoma brasiliensis Luque & Alves, 2003, also resembles the new genus but it lacks the lateral extensions of the trunk and the latter is cylindrical rather than flat. The second leg of the new genus is small and the endopod is shorter than the exopod. The other two genera have large second legs with subequal rami. KEY WORDS. Copepod parasite, chondracanthid, Southern Brasil, South Atlantic. RESUMO. Brasilochondria riograndensis gen. nov nov.. , sp. nov nov.. (Copepoda, Chondracanthidae), um parasito do linguado, Paralichthys orbignyanus (Valenciennes, 1839), é descrito. O novo gênero tem uma cabeça esférica, um “pescoço” pós-mandíbular e dois pares de pernas que são birremes e modificados na fêmea. Nestes aspectos, ela parece com Argentinochondria patagonensis Etchegoin, Timi & Sardella, 2003. Nesta, no entanto, a cabeça é esférica com uma constrição medial e na parte posterior do tronco faltam as extensões póstero-laterais que o novo gênero possui. Pseudolernentoma brasiliensis Luque & Alves, 2003, é também parecido com o novo gênero, mas carece das extensões póstero-laterais e o mesmo tronco é cilíndrico em vez de achatado. A segunda perna no novo gênero é pequena e o endopodito é mais curto que o exopodito. Nos outros dois gêneros, as segundas pernas são grandes e os ramos são sub-iguais. PALAVRAS CHAVE. Copépodo parasito, chondracanthídeo, Sul do Brasil, Atlántico Sul. Chondracanthidae is a family of copepods found parasitizing marine fishes throughout the world. YAMAGUTI (1963) listed 37 genera and 133 species in this family with a majority of species ascribed to Acanthochondria Oakley, 1927 (48) and Chondracanthus Delaroche, 1811 (27). Since that time, a few additional genera and species have been described. HO (1994) offered a key to 41 genera of chondracanthids. BOXSHALL & MONTÚ (1997) listed only two representatives of this family for Brazil, namely, Blias prionoti Kroyer, 1863, and Chondracanthus merluccii (Holten, 1802). Recently, ETCHEGOIN et al. (2003) described a new genus and species, Argentinochondria patagonensis, from a marine fish of Patagonia. LUQUE & ALVES (2003) proposed a new genus and species that they called, Pseudolernentoma brasiliensis from a marine fish of Rio de Janeiro State, Brazil. ALVES et al. (2003) described a new species, Acanthochon- dria triangularis from a Brazilian coastal fish. The present paper describes a new genus and species of Chondracanthidae from flounders of Rio Grande do Sul State, Brazil. MATERIAL AND METHODS Fish hosts were netted in the sea near Rio Grande in Rio Grande do Sul State, Brazil. The copepods were removed from the gills and the inner sides of the opercula by means of dissecting needles and fixed in 70% ethanol. The specimens were cleared in pure phenol for study. Digital photographs were made at five megapixels. Measurements were obtained with a measuring ocular and are expressed in microns (µm) unless indicated as millimeters (mm). Extremes are followed by the means in parentheses. Revista Brasileira de Zoologia 21 (3): 515–518, setembro 2004 516 V. E. Thatcher & J. Pereira Jr. 11 12 2 1 3 13 14 5 15 10 6 7 4 8 9 16 17 Figures 1-17. Brasilochondria riograndensis sp. nov. (1-9) Female: (1) entire, ventral; (2) antennule; (3) antenna; (4) egg sac; (5) mandible; (6) maxillule; (7) maxilla; (8) leg 1; (9) leg 2; (10-16) male: (10) entire, lateral; (11) mandible; (12) maxillule; (13) maxilla; (14) antenna; (15) antennule;(16) maxilliped, male; (17) maxilliped, female. Scale bars: 1 = 2000 mm; 2, 3, 8, 11-15 and 17 = 100 mm; 4 = 1000 mm; 5-7, 16 = 50 mm; 9 = 200 mm; 10 = 200 mm. RESULTS Brasilochondria riograndensis sp. nov nov.. Brasilochondria gen. nov nov.. Figs 1-21 Female: Body consisting of a spherical cephalothorax, elongate, cylindrical, post-mandibular “neck” and flattened trunk. Head composed of cephalosome only; “neck” formed from first two pedigerous segments; trunk extended posterolaterally on either side. Leg 1 small, immediately behind head, biramous, rami flattened; leg 2 just anterior to trunk, biramous. Egg sacs elongate, cylindrical, multiseriate. Male: Dwarf, with expanded cephalothorax; body segmentation indistinct; genitoabdomen terminates in two spiniform caudal rami. Antennule short and cylindrical; antenna uncinate and robust. Legs 1 and 2 represented by simple lobes. Type and only species: Brasilochondria riograndensis sp. nov. Female (10 measured: Figs 1-9, 17-18, 20-21) Total length, 11.4-16.4 (13.6) mm; maximum width at mid-level of trunk, 2.1-3.4 (2.8) mm. Cephalothorax spherical, 1.39-2.46 (1.90) mm in diameter, bearing antennae and mouthparts; antennule short, cylindrical with few spines terminally, 210-280 (252) long and 50-100 (76) in diameter: antenna hook-like, 260-325 (294) long by 140-165 wide. Mouthparts (Figs 5-7) of typical poecilostome form. Maxilliped of three articles. Neck cylindrical, expanding posteriorly, 462-616 (519) in diameter and 4.62-7.82 (5.62) mm in length. Neck bearing two pairs of modified legs; leg 1 of two flattened rami, endopod 190-325 (240) long and 85-175 (128) wide; exopod 180-350 (256) long by 100-175 (165) wide: leg 2 Revista Brasileira de Zoologia 21 (3): 515–518, setembro 2004 Brasilochondria riograndensis gen. nov nov.. , sp. nov nov.. a parasite of flounders... 517 18 20 19 21 Figures 18-21. Brasilochondria riograndensis sp. nov.: (18-19) posterior extremity of female with attached male; (20) cephalothorax of female showing antennae and first pair of legs; (21) posterior extremity of female showing postero-lateral extensions and caudal projection. Scale bars: 18 and 21 = 500 mm, 19 = 200 mm, 20 = 1000 mm. of two tapered, cylindrical rami; endopod 125-225 (173) lo (...truncated)