Notorchestia naturaliste, Serejo & Lowry, 2008

Serejo, C. S. & Lowry, J. K., 2008, The Coastal Talitridae (Amphipoda: Talitroidea) of Southern and Western Australia, with Comments on Platorchestia platensis (Krøyer, 1845), Records of the Australian Museum 60 (2), pp. 161-206 : 185-188

Notorchestia naturaliste n.sp.

Figs 17–20

Type material. HOLOTYPE: male, 14.8 mm, AM P69121 (1 slide, stubs J046–J049–J052) . PARATYPES: 1 male, 16.2 mm, AM P69122 (stub J061, habitus) ; 1 juvenile male, 15.5 mm, AM P69123 ; 1 female 14.6 mm, AM P69124 ; (stub J048, SEM micrographs) ; 10 males and 90 females, AM P69125 ; all from Bunker Bay, Cape Naturaliste , Western Australia (33°32.39'S 115°1.8'E), protected small rocky beach, C. Serejo & J.K. Lowry, 24 Oct. 2003, WA 760 .

Type locality. Bunker Bay, Cape Naturaliste , Western Australia (33°32.39'S 115°1.8'E) .

Additional material examined. Western Australia: 8 males and 30 females (multicoloured), AM P69126 , Blackwood River mouth, Augusta (34°19.54'S 115°10.07'E), flat beach near boat ramp, substrate coarse dark sand with some tan to orange and almost black pebbles, substrate covered with large patches of a green alga, probably Enteromorpha, C. Serejo & J.K. Lowry , 23 Oct. 2003, WA 758 ; 6 males and 52 females, AM P69127 , Slippery Rock, Cape Leuwin (34°21.44'S 115°7.64'E), mixed and dead seaweed lodged between large boulders at the end of a steeply sloping white sand beach, C. Serejo & J.K. Lowry, 23 Oct. 2003, WA 759 ; 1 male, 1 female and 2 juvenile males, AM P69128 , beach, Freshwater Point (29°36.34'S 114°58.42'E), small sandy beach with a lot of dead seagrass and seaweed adjacent to a rocky point, C. Serejo & J.K. Lowry, 28 Oct. 2003, WA 766 ; 6 males, AM P69129 , Denham Beach, Denham, Shark Bay (25°56'S 113°32.53'E), white sandy beach with a strand of dead seagrasses at the high tide mark, C. Serejo & J.K. Lowry, 5 Nov. 2003, WA 776 .

Etymology. This species is named for Cape Naturaliste, the type locality.

Diagnosis. Dactylus of gnathopod 1 with row of ventral short setae. Female and male juvenile gnathopod 2 merus with distally pointed posterodistal medial lobe. Gnathopod 2 male, propodus subtriangular; palm acute and sinuous. Coxa 6 posterior lobe posteroventral margins with 6–7 robust setae. Basis of pereopod 7 with lateral sulcus. Telson cleft to half length.

Description

Holotype male, 14.8 mm. Eye medium, 1⁄5–1/3 head length. Antenna 1 short, rarely longer than peduncle article 4 of antenna 2. Antenna 2 shorter than head and first 3 pereonites; peduncular articles narrow; with many robust setae; article 5 longer than article 4. Epistome of upper lip without robust setae. Lower lip distolateral setal tuft absent. Mandible left lacinia mobilis 4-dentate. Maxilliped palp article 2 with distomedial lobe, article 4 present, reduced.

Gnathopod 1 sexually dimorphic; subchelate; posterior margin of carpus and propodus with rugose lobe; propodus sub-triangular; palm transverse; dactylus shorter than palm, with row of ventral short setae. Gnathopod 2 sexually dimorphic; subchelate; merus without posterodistal medial lobe; carpus triangular, reduced, enclosed by merus and propodus; propodus sub-triangular; palm acute, sinuous, with small midpalmar concavity, posterodistal corner without protuberance; dactylus longer than palm, not attenuated distally. Coxae 2–4 as wide as deep. Pereopods 3–7 cuspidactylate; dactylus with row or patch of dorsal short setae. Pereopod 4 significantly shorter than pereopod 3. Pereopod 4 dactylus thickened and pinched posteriorly, different to pereopod 3 dactylus. Pereopod 5 propodus distinctly longer than carpus. Pereopod 6 not sexually dimorphic; shorter than pereopod 7; coxa posterior lobe anterodistal corner rounded, posteroventral margins with 6–7 robust setae, outer surface with ridge. Pereopod 7 sexually dimorphic; basis with lateral sulcus well developed, posterodistal lobe absent; distal articles slender. Coxal gills simple or slightly lobate. Pereopods 3–5 gills smaller than gills 2 and 6.

Pleopods 1–3 well developed, biramous. Pleopod 1 peduncle without setae; pleopods 2–3 peduncles with 5–6 short marginal robust setae. Epimeron 2 subequal in length to epimeron 3. Epimeron 3 posterior margin with setae, posteroventral corner with small subacute spine. Uropod 1 peduncle with 12 robust setae in two rows; distolateral robust seta absent; inner ramus subequal in length to outer ramus; inner ramus with 4 marginal robust setae; outer ramus with 4 marginal robust setae. Uropod 2 peduncle with 11 robust setae in two rows; inner ramus subequal in length to outer ramus, with 5 marginal robust setae; outer ramus with 2 marginal robust setae. Uropod 3 peduncle with 4 robust setae; ramus shorter than peduncle; oval to spatula-shape, broad distally; ramus with 5–6 marginal setae and 4–5 apical setae. Telson longer than broad; incised to half length; with marginal and apical robust setae, about 3 to 5 robust setae per lobe.

Female (sexually dimorphic characters), 14.6 mm. Gnathopod 1 parachelate; posterior margin of merus, carpus and propodus without rugose lobe; propodus ovoid; palm very short, acute; dactylus longer than palm, with row of ventral short setae. Gnathopod 2 basis slightly expanded, about 2× longer than wide; merus with distally pointed posterodistal medial lobe; palm obtuse, smooth; dactylus shorter than palm. Pereopod 7 basis with lateral sulcus slightly pronounced. Oostegites longer than wide; setae with simple and/or multi-furcate tips. Oostegites 2–4 moderately setose (around 24 setae).

Variation. In juvenile males the process on the merus of gnathopod 2 may be present; the palm of gnathopod 2 is nearly straight and the sulcus on basis of pereopod 7 is slightly pronounced.

Remarks. Notorchestia naturaliste n.sp. resembles N. lobata n.sp. in the short antenna 1; heavily setose antenna 2; male gnathopod 1 subchelate, with rugose lobe on carpus and propodus; basis of pereopod 7 with lateral sulcus; and cleft telson. However, N. naturaliste can be distinguished from N. lobata by the sub-triangular shape of propodus of gnathopod 2 (not subquadrate), palm of gnathopod 2 with shallow concavity (not strong concavity in adult males); coxa 6 posterior lobe posteroventral margins with 6–7 robust setae, (not 14–15 setae); basis of pereopod 7 without posteroventral lobe on posterior margin, but with a frontal facial lobe formed from the sulcus ( Fig. 18 ). Notorchestia naturaliste n.sp. occurred only in Western Australia and was found living sympatrically with N. lobata at Slippery Rock, Cape Leuwin.

Distribution. Western Australia: Blackwood River mouth; Slippery Rock, Cape Leuwin; Bunker Bay, Cape Naturaliste; Freshwater Point; Denham Beach, Denham, Shark Bay.

Figures

Fig. 17. Notorchestia naturaliste n.sp., paratype male, 16.2 mm, habitus, AM P69122; holotype male 14.8 mm, other parts, AM P69121, Bunker Bay, Cape Naturaliste, Western Australia. Scales for habitus: 1 mm; H: 0.5 mm; UL, MD, MX2, MP: 0.1 mm; MX1: 0.06 mm.

Fig. 18. Notorchestia naturaliste n.sp., holotype male, 14.8 mm, AM P69121, Bunker Bay, Cape Naturaliste, Western Australia. Scales for G1 and P4: 0.2 mm; remainder: 0.5 mm.

Fig. 19. Notorchestia naturaliste n.sp., holotype male, 14.8 mm, U1–3, EP1–3, T, AM P69121, paratype female, 14.6 mm, G1–2, AM P69124, Bunker Bay, Cape Naturaliste, Western Australia. Scales for U1–3: 0.2 mm; G1–2: 0.3 mm; EP1–3: 0.5 mm; T: 0.1 mm.

Fig. 20. Notorchestia naturaliste n.sp. paratype female 14.6 mm, O2–5, BR2–6, AM P69124, holotype male, 14.8 mm, PL1–3, AM P69121, Bunker Bay, Cape Natu- raliste, Western Australia. Scales represent 0.2 mm.