Parastenhelia gracilis Brady 1910

• Main Authors: Huys, Rony, Mu, Fanghong
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2021
• Subjects: Biodiversity; Taxonomy; Animalia; Arthropoda; Hexanauplia; Harpacticoida; Parastenheliidae; Parastenhelia; Parastenhelia gracilis; Antarc*; Antarctica; Tierra del Fuego
• Online Access: https://doi.org/10.5281/zenodo.5572450; http://treatment.plazi.org/id/951887EAFFE9FFB5FF51D7B2E705FAC1

Parastenhelia gracilis Brady, 1910 and other subantarctic records of Parastenhelia Microthalestris gracilis (Brady, 1910) comb. nov. belongs to a close-knit group of subantarctic species characterized by the position of the inner seta on P1 enp-1 which originates from the middle third of the segment. This subantarctic group includes M. gracilis , M. antarctica (Scott, 1912) comb. nov. , M. costata (Pallares, 1982) comb. nov. , M. santacruzensis sp. nov. and M. variabilis sp. nov. In all other members of the genus the inner seta of P1 enp-1 is situated further proximally, at around 25% the length of the inner margin of the segment. Interestingly, the latter condition is also displayed by M. minuta (Pallares, 1982) comb. nov. from Tierra del Fuego and M. campbelliensis sp. nov. from Campbell Island, suggesting the independent colonization of the subantarctic region by two different lineages. Microthalestris gracilis comb. nov. is known from a single female collected in the Baie de l’Observatoire (Observatory Bay) along the northern shore of the Golfe du Morbihan in the Kerguelen (Brady 1910: 513; Textfig. VIII). A second record by Jayabarathi (2016) from seagrass beds in South Andaman is highly questionable. The original description includes illustrations of the antennule, P1, P2, P5 and caudal rami but is deficient in many aspects. The armature is unknown for P3–P4 except for Brady’s (1910) dubious claim that their distal endopodal segments have only three elements. The P2 is shown to have two inner setae on exp-3 which is also questionable. Since within the Parastenheliidae this condition is only found in members of Thalestrella and Foweya (Table 1) it may indicate that Brady’s (1910) illustration is either based on an observational error or in reality refers to P3 or P4. Alternatively, the possibility that P. gracilis represents a member of Foweya cannot be excluded but this would require information on the male and the sexual dimorphism in this species. Another unusual feature of P. gracilis is the endopodal ...