Pandarus Leach, 1816 (Copepoda: Siphonostomatoida: Pandaridae) species collected from elasmobranchs off South Africa with the description of Pandarus echinifer n. sp.

Syst Parasitol (2024) 101:46 https://doi.org/10.1007/s11230-024-10167-y Pandarus Leach, 1816 (Copepoda: Siphonostomatoida: Pandaridae) species collected from elasmobranchs off South Africa with the description of Pandarus echinifer n. sp. S. M. Dippenaar Received: 7 March 2024 / Accepted: 24 April 2024 © The Author(s) 2024 Abstract Eight species of Pandarus Leach, 1816 collected from hosts caught off South Africa are reported. These species include P. bicolor Leach, 1816, P. niger Kirtisinghe, 1950 and P. carcharhini Ho, 1963 belonging to the “bicolor” group and P. cranchii Leach, 1819, P. satyrus Dana, 1849, P. smithii Rathbun, 1886 and P. sinuatus Say, 1818 belonging to the “cranchii” group. Notes on previous and new distinguishing features are provided with illustrations, specifically the relative lengths of the dorsal plates and caudal rami as well as the structure of the distomedial spine on the second segment of leg 1 exopod. Additionally, illustrated re-descriptions are provided for P. satyrus and P. sinuatus. Furthermore, a new species Pandarus echinifer n. sp., also belonging to the “cranchii” group, collected from the snaggletooth shark Hemipristis elongata (Klunzinger) is described. This species is most similar to P. sinuatus but can be distinguished from it by the heavily spinulated distomedial spine on the last segment of the first leg exopod. Molecular analysis of the cytochrome oxidase I partial gene is used to calculate sequence divergences amongst different individuals and species. According to the results (as well as based on morphological characters) P. rhincodonicus Norman, Newbound & Knott, 2000 is a synonym of P. S. M. Dippenaar (*) Department of Biodiversity, University of Limpopo, Private Bag X1106, Sovenga 0727, South Africa e-mail: cranchii. New hosts and geographic localities from South Africa (and Ningaloo Park, Western Australia) are reported. Introduction Pandarus Leach, 1816 is one of the 23 genera of the family Pandaridae Milne Edwards, 1840 (Walter & Boxshall 2024) mostly infecting elasmobranchs, with Pandarus specimens commonly found on the body surface of the host (Cressey 1967; Kabata 1979). Currently there are 14 accepted species of Pandarus (Walter & Boxshall 2024), namely P. bicolor Leach, 1816; P. sinuatus Say, 1818; P. cranchii Leach, 1819; P. rouxii Risso, 1826; P. satyrus Dana, 1849; P. zygaenae Brady, 1883; P. brevicaudis Dana, 1852–1853; P. smithii Rathbun, 1886; P. ambiguus (Scott T., 1907); P. niger Kirtisinghe, 1950; P. carcharhini Ho, 1963; P. floridanus Cressey, 1967; P. katoi Cressey, 1967, and P. rhincodonicus Norman, Newbound & Knott, 2000. However, in the revision of the pandarids, Cressey (1967) made no mention of P. rouxii, P. brevicaudis or P. ambiguus. Carus (1885) referred to P. rouxii as a “species non determinanda” and thus should be a species inquirenda. Additionally, P. brevicaudis was accepted by Wilson (1907) as a valid species and described the female and male based on specimens described by Dana (1853) as P. brevicaudis and Nogagus validus, respectively. However, comparing Dana’s (1853) Vol.: (0123456789) 13 46 Page 2 of 21 illustrations (see Figs. 2a and 3a on plate 95) of the females of P. satyrus and P. brevicaudis respectively, it is obvious that Fig. 3a represents an immature female. Wilson (1907) also mentioned P. brevicaudatus from Bassett-Smith (1899) as a synonym of P. brevicaudis which Bassett-Smith (1899) referred to as “imperfectly described”. Thus, P. brevicaudis should also be regarded as a species inquirenda. Regarding P. ambiguus described as Nogagus ambiguus in Scott & Scott (1913), the description and illustrations (see Figs. 1–8 of plate XX) is that of an immature pandarid (cf. Fig. 5A in Izawa (2010)), most likely a male due to the claw on the maxilliped (see Fig. 4). Comparing this description and illustration with those of the copepodid stages of male and female P. cranchii (Izawa 2010) discrepancies are observed especially regarding the structure of leg 4 of N. ambiguus (i.e. P. ambiguus) (see Fig. 8 of plate XX in Scott & Scott (1913)) with a 1-segmented exopod and 2-segmented endopod while leg 4 of the copepodid stages and adult female of P. cranchii have 1-segmented rami and the adult male has 2-segmented rami, similar to the adults of other Pandarus species (Cressey 1967). Therefore, P. ambiguus should also be regarded as a species inquirenda and consequently there are currently only 11 valid species. According to Cressey (1967), the adult females can be divided into two groups based on their dorsal morphology, i.e., the “bicolor” group with the dorsal plates of thoracic somite two that extends only up to the posterior edge of the plate of somite three (including P. bicolor, P. niger, P. carcharini) and the “cranchii” group with the dorsal plates of the thoracic somite two extending well beyond the posterior edge of that of somite three (including P. sinuatus, P. cranchii, P. satyrus, P. zygaenae, P. smithii, P. floridanus, P. katoi and P. rhincodonicus). The three species in the “bicolor” group can be distinguished from each other mainly by the lengths of the caudal rami with those of P. bicolor barely visible in dorsal view, those of P. carcharhini just extending beyond the abdominal plate and those of P. niger extending well beyond the abdominal plate (Kirtisinghe 1950; Ho 1963; Cressey 1967). In the “cranchii” group, P. satyrus, P. cranchii and P. rhincodonicus are morphologically very similar (Cressey 1967; Norman et al. 2000) as are P. floridanus and P. sinuatus; and P. katoi and P. zygaenae (Cressey 1967) while P. smithii can be distinguished from all the other Vol:. (1234567890) 13 Syst Parasitol (2024) 101:46 species in the “cranchii” group by the presence of basal medial expansions on the caudal rami (Izawa 2010). However, Pandarus species undergo considerable morphological changes during their ontogeny (Kabata 1979) as well as varying signs of pigmentation (Ho 1963; Cressey 1967; Kabata 1979) and therefore using their dorsal features for species identification may result in misidentifications. Additionally, the setation of the limbs also exhibits variability (Hewitt 1967) with some species having the same spine and setal formulas (Cressey 1967). Current reports of Pandarus species from South African waters include P. bicolor from Carcharias sp., dogfish, Galeorhinus galeus (Linnaeus), Odontaspis sp., Squalus acanthias (Linnaeus) (Dippenaar 2004) and Carcharodon carcharias (Linnaeus), Mustelus palumbes Smith, Notorynchus cepedianus (Péron), and Triakis megalopterus (Smith) (Dippenaar 2024); P. carcharini from Carcharhinus leucas (Valenciennes) (Dippenaar 2004); P. niger from Carcharhinus obscurus (LeSueur) (Dippenaar 2024); P. cranchii from Carcharhinus longimanus (Poey), Carcharodon carcharias, Poroderma africanum (Gmelin), Sphyrna zygaena (Linnaeus), Stegostoma tigrinum (Foster), (Dippenaar 2004), Isurus oxyrinchus (Rafinesque) and Sphyrna lewini (Gr (...truncated)