Gondwanorchestia tristanensis, Myers & Pérez-Schultheiss, 2020

Myers, James K. Lowry Alan A. & Pérez-Schultheiss, Jorge, 2020, Gondwanorchestia tristanensis gen. nov. sp. nov., a new southern hemisphere genus and species of talitrid amphipod (Amphipoda, Senticaudata, Talitridae), Zootaxa 4748 (2), pp. 375-381 : 376-380

publication ID	https://doi.org/ 10.11646/zootaxa.4748.2.9
publication LSID	lsid:zoobank.org:pub:5E5C32F3-BB91-44E1-9B04-18D7A8D48A5F
DOI	https://doi.org/10.5281/zenodo.3704870
persistent identifier	https://treatment.plazi.org/id/6EC972F2-3044-4922-9C24-AE26F0FB1DFB
taxon LSID	lsid:zoobank.org:act:6EC972F2-3044-4922-9C24-AE26F0FB1DFB
treatment provided by	Plazi
scientific name	Gondwanorchestia tristanensis
status	sp. nov.

Treatment

Gondwanorchestia tristanensis View in CoL sp. nov.

( Figs 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Orchestia scutigerula View in CoL .― Stephensen, 1949: 26–29, figs 11, 12.― Macnae, 1953: 1027–1028.― Holdgate, 1965: 372.―K.H. Barnard, 1965: 207.

Type material. Holotype, male, 15.2 mm (NHMD-616083), Norw. Sci. Exped. 1937–38, Nightingale , Tristan da Cunha, St. 99, 5– 2–1938, 15 m. H.E. Sivertsen Leg.; paratype, female, 13.1 mm (NHMD-616084); paratypes, 2 males, 5 females (NHMD-88818), collection data same as for holotype . Paratypes, 1 male, 5 female and 1 juvenile male (NHMD-88819), Norw. Sci. Exped. 1937-38, Inaccessible Is., Tristan da Cunha, stn 1053, 7-3-1938, Y. Hagen Leg .

Material ( Stephensen 1949). Inaccessible: Stn 147, Bårdseth, a few specimens; stn 1008–1010, a few specimens; stn 1016, female, juvenile; stn 1022, 1 female; stn 1040, 2 specimens; stn 1042, 3 females; stn 1043, 2 females; stn 1045, 3 specimens ;; stn 1055, 2 specimens. Nightingale: stn 99, Sea Hen Rock, 5 December,1937, 15– 20 m above sea level, numerous specimens including male, ovigerous female and female with embryos; stn 502, 1 male; stn 506, several specimens; stn 509, several specimens including ovigerous female; stn 510, several specimens.

Type locality. Nightingale, Tristan da Cunha, Atlantic Ocean. Etymology. Named for the island group where the species lives. Description. Based on characters of the genus. Remarks. There is no information on habitat in the station list provided by Stephensen (1949). However, Macnae (1953) indicates that most specimens ‘were also caught at some distance from the sea, though some were found on the shore’. According to Macnae (1953) “the species lives some distance from the sea in penguin rooker-

ies, clumps of tussock grass, in Phylica woods on the higher parts of the island” and among albatross nests. Macnae considered it to be a fully terrestrial species.

Gondwanorchestia tristanensis sp. nov. differs from G. scutigerula (Dana) in a number of ways (based on unpublished illustrations of Hughes & Lowry, in prep.). In the male gnathopod 1 the basis is elongate and slender, whereas in G. scutigerula it is short and stout. In the male gnathopod 2, the propodus palm is strongly oblique and weakly convex, whereas in G. scutigerula it is weakly oblique and substraight; the dactylus is slender and distally acute, fitting closely against palm, whereas in G. scutigerula it is stout, distally blunt or weakly acute and does not fit closely against the palm. The coxa of pereopods 3 and 4 has a distinctive notch on the anterior margin, whereas in G. scutigerula the coxa lacks the notch. The carpus of pereopod 3 is similar in size to that of pereopod 4, whereas in G. scutigerula the carpus of pereopod 3 is longer than that of pereopod 4. In pereopod 5, the posterodistal lobe of the basis is well developed, whereas in G. scutigerula it is poorly developed. The peduncle of uropod 3 has a single distal seta, whereas in G. scutigerula there are 3 setae. The telson carries about 7 setae on each lobe, whereas in G. scutigerula each lobe carries up to 11 setae.

Distribution. Penguin and Midshipman Islands (K.H. Barnard 1965); Inaccessible and Nightingale Islands ( Macnae 1953, Stephensen 1949).