Pickorchestia Lowry & Myers, 2019

Lowry, J. K. & Myers, A. A., 2022, Platorchestiinae subfam. nov. (Amphipoda, Senticaudata, Talitridae) with the description of three new genera and four new species, Zootaxa 5100 (1), pp. 1-53 : 37

Pickorchestia Lowry & Myers, 2019

Pickorchestia Lowry & Myers, 2019: 71 .

Type species. Orchestia pickeringi Dana, 1853 , monotypy.

Included species. Pickorchestia includes 1 species: P. pickeringi ( Dana, 1853) .

Category. Mascupod.

Ecological type. Field-hopper, moss-hopper.

Habitat. Pickorchestia pickeringi is a terrestrial land-hopper living on Mount Ka’ala, O’ahu at 853 m altitude, in the axils of Astelia , but also collected widely in the Ko’olau Mountains at high altitudes, usually in the axils of Freycinetia arborea .

Diagnostic description (male). Based on Richardson (1991).

Head. Antenna 2 peduncular articles slender. Mandible left lacinia mobilis 5-cuspidate (fifth tiny). Labium without inner lobes. Maxilliped palp article 2 with distomedial lobe; article 4 reduced, button-shaped.

Pereon. Gnathopod 1 sexually dimorphic, subchelate; posterior margin of carpus and propodus each with lobe covered in palmate setae; propodus anterior margin with 3 groups of robust setae, ‘subtriangular’ with well-developed posterodistal lobe, palm transverse. Gnathopod 2 subchelate; propodus palm slightly acute, irregular, with small mid-palmar sinus, a shallow sinus near dactylar hinge and a shallow distal sinus; without proximal spine or thumb defining palm; dactylus not modified distally, blunt. Pereopods 3–7 dactyli bicuspidactylate. Pereopod 4 dactylus homobasidactylate, similar to pereopod 3 dactylus, not thickened proximally or notched. Pereopod 5 short, less than 2/3 length of pereopod 6; merus broad, long than broad, expanded distally. Pereopod 6 subequal in length to pereopod 7, not incrassate; basis moderately expanded; male merus and carpus not expanded. Pereopod 7 not incrassate; basis broadly expanded; merus unexpanded; carpus unexpanded; propodus without large distal tuft of setae. Oostegites (female) setae with simple smooth tips.

Pleon. Pleopods all slightly reduced. Uropod 1 peduncle distolateral robust seta absent; exopod without marginal robust setae; endopod with marginal robust setae in 1 row. Uropod 2 exopod with marginal robust setae in 1 row; endopod with marginal robust setae in 2 rows. Uropod 3 ramus shorter than peduncle. Telson apically incised, with 3–6 robust setae per lobe or with 7–9 robust setae per lobe.

Remarks. Based on gnathopod 2 with a small midpalmar sinus (apomorphic), pereopod 4 dactylus homobasidactylate (apomorphic) and uropod 1 exopod without marginal robust setae (apomorphic) Pickorchestia appears to be a sister taxon to Platorchestia .

Distribution. Hawaii. Oahu, ( Richardson, 1991).