Platorchestia negevensis, Myers & Lowry, 2023

Myers, Alan A. & Lowry, James K., 2023, The Beach-hopper Genus Platorchestia (Crustacea: Amphipoda: Talitridae) on Atlantic Ocean Coasts and on those of Associated Seas, Records of the Australian Museum (Rec. Aust. Mus.) 75 (4), pp. 485-505 : 497-499

Platorchestia negevensis sp. nov.

urn:lsid:zoobank.org:act:C3C933AB-5955-4BBD-9EF6-47B294CF746F

Figs 10–11

Orchestia platensis .— Herbst & Dimentman, 1983: 20, fig. 3 (in part).

Platorchestia monodi .— Morino & Ortal, 1995: 825, figs 1–3.

Not Orchestia platensis Krøyer, 1845: 304 , pl. 2 figs 2a–i.

Not Orchestia monodi Mateus, Mateus & Afonso, 1986: 100, figs 1–7.

Syntypes: 3 males (8.0– 9.5 mm), 2 females (7.7–8.5 mm), En Hameara , Negev Desert, Israel, IES 2088 Amp 1246 and IES 5352, Hebrew University of Israel .

Type locality. En Hameara, Negev Desert, Israel.

Etymology. Named after the Negev Desert in which the type locality is located.

Ecological type. Riparian-hopper.

Description. Based on figures of Morino & Ortal (1995) (male 9.5 mm).

Head. Eyes black, large. Antenna 1 shorter than article 4 of antenna 2. Antenna 2 peduncle very weakly incrassate; article 5 longer than 4; peduncular articles with sparse, small robust setae.

Pereon. Gnathopod 1 subchelate; posterior margin of carpus and propodus with rugose lobe; carpus 3 × longer than its median width, rugose lobe broad; propodus subtriangular; dactylus cuspidactylate, shorter than palm. Gnathopod 2 sexually dimorphic; subchelate; basis weakly expanded, parallel-sided; merus without medial lobe; carpus reduced, enclosed by merus and propodus; propodus subovate, posterior margin nearly straight; palm acute, convex, with small notch and protuberance near posterodistal corner; dactylus scythiform, overlapping posterior margin. Coxae 2–4 as wide as deep. Pereopods 3–7 cuspidactylate; Pereopod 4 significantly shorter than pereopod 3; dactylus short with mini-wavy posterior margin. thickened but not pinched different from that of pereopod 3. Pereopod 5 propodus longer than carpus. Pereopod 6 shorter than pereopod 7, not sexually dimorphic, coxa posterior lobe without process. Pereopod 7 not incrassate; basis a little longer than broad, posterodistal lobe present.

Pleon. Epimera 1–3 with posterior margin slightly serrated, posteroventral corners produced. Uropod 1 peduncle with robust setae in two rows, distolateral robust seta absent; rami three quarters length of peduncle; endopodite subequal in length to exopodite with 4 marginal inner setae and 4 marginal outer setae; exopodite without marginal setae. Uropod 2 peduncle inner margin with 5 setae; outer margin with 3 or 4 strong, robust setae; endopodite subequal in length to exopodite with two rows of 3 marginal robust setae; exopodite with 2 marginal robust setae. Uropod 3 peduncle a little longer than ramus, with 3 robust setae; ramus almost parallel-sided; with 2 marginal setae, and 2 or 3 apical setae. Telson longer than broad, apically incised, with marginal and apical robust setae; each lobe with 5–7 robust setae per lobe.

Female (sexually dimorphic characters). Gnathopod 1 carpus and propodus without rugose lobes. Gnathopod 2 mitten-shaped; basis anterior margin irregularly notched, weakly convex proximally, anteriorly nearly straight.

Habitat. Near springs and wells ( Morino & Ortal, 1995). Restricted to enclosed perpetually moist habitats such as wells or small springs in caves. It displays an amphibious lifestyle, often being collected in debris and moist sandy soil outside the water ( Herbst & Dimentman, 1983).

Remarks. Platorchestia negevensis sp. nov. resembles P. platensis ( Krøyer, 1845) from which it was probably derived during a sea-level regression. It differs in having a neotenous, non-incrassate condition of pereopod 7. It is the only Atlantic species that has this character state neotenous, but the state does occur in some non-Atlantic species ( P. ano Lowry & Bopiah, 2013 , P. pachypus Derzhavin, 1937 and P. smithi Lowry, 2012 ). It differs from P. ano in the relatively short carpus of gnathopod 1 and the poorly incrassate male antenna 2. Both P. pachypus and P smithi , unlike P. negevensis sp. nov., have a strongly incrassate male antenna 2. The dactylus of the male gnathopod 1 of P. negevensis sp. nov. is distinctly shorter than the palm, whereas in P. platensis it is scarcely shorter than the palm.

Distribution. Israel: Sinai and Negev Deserts ( Herbst & Dimentman, 1983; Morino & Ortal, 1995).

Figures

Figure 10. Above Platorchestia griffithsi sp. nov., male holotype (9 mm), Knysna lagoon, South Africa; below P. negevensis sp. nov., male (9.5 mm), Negev desert (after Morino & Ortal, 1995).

Figure 11. Platorchestia negevensis sp. nov., male (9.5 mm), female (8.5 mm), Negev desert (after Morino & Ortal, 1995).