Paratya rouxi, Suter & Mynott & Crump, 2022

Suter, Phillip J., Mynott, Julia H. & Crump, Megan, 2022, New species of Paratya (Decapoda: Atyidae) from Australian inland waters - linking morphological characters with molecular lineages, Memoirs of Museum Victoria (Mem. Mus. Vic.) 81, pp. 55-122 : 101-105

Paratya rouxi n. sp.

Figures 27–29

http://zoobank.org/ urn:lsid:zoobank.org:act:8319F351-EA76-

4AF9-9C63-63F0CEB5E292

P. australiensis Roux

Lineage 9 ( Cook et al., 2006)

Type Material: Holotype New South Wales. Wakool Reserve , − 35.496 S, 144.454 E, June 2011 ( JC). Body in ethanol and antennae, mouthparts, pereiopods and abdominal structures dissected, mounted on 2 slides. AM Ref No. P. 105605, Accession Ref. MC83 , Genbank Registration OL 420861.

Paratypes: New South Wales. Wakool Reserve , − 35.4963 S, 144.4541 E, June 2011 Accession Ref. MC672 Genbank Registration OL 420849, PS1 – PS2 ( JC), Bodies in ethanol and other structures dissected, mounted on 2 slides each .

Material Examined: As for type material.

Diagnosis: P.rouxi differs from all other species by the following combination of characters: rostrum very short, extending just beyond the first segment of the antennular peduncle, rostrum short and broad with a downward curve, dorsally armed with 11–19 spines, 0 postorbital spines, ventrally with 1–2 spines over a length of less than 0.4 mm, all forward of greatest depth; distal half of ventral edge straight, rostral length 0.57–0.73 times length of scaphocerite; left mandible with 4 teeth in two groups separated by smooth U-shaped notch from a distinct apical tooth; right mandible with 4 teeth in two separate incisor processes; scaphognathite of maxilla 2 truncated apically with an inner lobe almost extending to apex of upper endite; maxilliped 1 with exopod flagellum distinct, well developed and with numerous long setose spines on all margins, over half length of caridean lobe; exopod of maxilliped 2 1.9–2.7 times longer than endopod, epipodite with long podobranchs extending to basal third of third segment of endopodite; maxilliped 3 with medial distal margin of apical segment of endopod with 7–10 broad teeth-like spines, outer margin with 2 long teeth-like spines near terminal spine and 1 mid outer spine, exopod long and narrow, tip over-reaching distal end of basal endopod segment; pereiopod 1 with long carpus and long slender chelae; pereiopod 2 with exopod extending to mid merus; dactylus of pereiopod 3 with prominent terminal claw and 10–12 strong spines on medial margin, exopod extends to mid merus; dactylus of pereiopod 4 prominent terminal claw and 8–12 spines on medial margin, exopod extends to apical third of merus; dactylus of pereiopod 5 with prominent terminal claw and very regular comb–like row of 70–80 small spines on medial margin, exopod extends to mid merus.

Carapace length 4.90 (4.90–5.30) mm.

Rostrum very short (fig. 27a), 2.70 (2.10–2.75) mm long, extending just beyond the first segment of the antennular peduncle, 0.55 (0.49–0.55) times length of carapace, shape convex, short and broad with downward curve, pointed; rostrum 6.75 (5.00–6.75) longer than wide; dorsally armed with 19 (11– 19) spines (fig. 27a), ratio of dorsal spine number to length is 7.04 (4.61–7.04) without postorbital eye spines; ventrally with 1 (1–2) spines over a length of 0.10 (0.10–0.40) mm, all anterior to greatest width; distal half of ventral edge straight, ratio of ventral spines length to rostral length is 0.03 (0.04–0.15) and 19.00 (6.00–19.00) more dorsal spines than ventral spines; rostral length 0.73 (0.57–0.73) times length of scaphocerite.

Antenna 1 (fig. 27b) peduncle short, 3.24 (3.24–3.64) mm long, not reaching distal tip of scaphocerite, 0.88 (0.88–0.98) times scaphocerite length. Stylocerite 1.80 (1.80–2.03) mm long, length 11.25 (9.00–11.25) longer than wide, 0.37 (0.34–0.38) times carapace length, just reaching beyond distal border of peduncle segment and to base of distal angle process (fig. 24c).

Antenna 2 (fig. 27c) second segment 1.16 (1.00–1.30) mm long, 0.31 (0.27–0.34) times length of scaphocerite and 2.42 (2.42–2.50) times width. Scaphocerite 3.70 (3.65–3.80) mm long, 0.76 (0.70–0.76) times carapace length and 3.36 (2.71– 3.36) times as long as wide.

Mouthparts. Left mandible (fig. 27d, e) with incisors of 4 teeth (2 large teeth and 2 robust teeth (one small and one large) at base), separated from a large acute apical tooth by a smooth U-shaped notch. Spine row with 9 spines, each finely setose, spine row above molar process of approximately over 40 sparsely setose spines. Right mandible (fig. 27f, g) with 4 teeth in 2 separate incisor processes with apical and second teeth large. Spine row immediately below teeth with 12 spines each finely setose, spine row above molar process. Molar process ridged.

Maxilla 1 (fig. 27h) as for P. australiensis .

Maxilla 2 (fig. 27i) scaphognathite apex truncated with an inner lobe, almost extending to apex of endite.

Maxilliped 1 (fig. 27j) as for P. australiensis .

Maxilliped 2 (fig. 27k) endopod 0.80 (0.76–0.84) mm long; exopod length 2.07 (1.60–2.07) mm, long and narrow, exopod 2.58 (1.90–2.71) longer than endopod. Epipodite with long podobranch extending to basal third of third segment of endopodite.

Maxilliped 3 (fig. 28a) endopod 5.36 (5.36–5.95) mm long, 2.51 (2.07–2.51) times longer than exopod; basal segment curved, apical segment with large terminal claw, medial distal margin with 8 (8–10) broad teeth-like spines, largest 3 in mid half and 1 long spine in basal third, outer margin with 1 long tooth-like spines near terminal spine and 1 mid outer spine. Exopod 2.13 (2.13–2.88) mm long, narrow, tip over-reaching distal end of basal endopod segment.

Thoracic appendages. Pereiopod 1 (fig. 28b) short, 3.92 (3.92–4.25) mm long, 0.80 (0.74–0.85) times carapace length. Chelae short and slender (fig. 28b), 1.33 (1.25–1.35) mm long, propodus 3.85 (3.10–3.85) times as long as wide, propodus length 2.17 (1.92–2.17) times longer than dactylus; palm length 2.11 (1.90–2.11) times palm width, 1.36 (1.06–1.36) times dactylus length. Carpus long, 2.33 (2.33–3.00) times longer than greatest width. Segment ratios 0.66 (0.54–0.66): 1.43 (1.16–1.43): 1.00 (0.93 [0.93–1.13] mm): 1.33 (1.15–1.33): 0.44 (0.40–0.45): –. Exopod extending to mid-apex of carpus.

Pereiopod 2 (fig. 28c) longer than pereiopod 1, 6.00 (6.00–6.90) mm long, 1.22 (1.19–1.38) times carapace length. Chelae long and slender (fig. 28c), 1.33 (1.28–1.33) mm long, half to two-thirds length of carpus, 4.00 (3.63–4.00) times as long as wide, palm length 2.38 (2.22–2.38) times palm width, 1.27 (1.25–1.27) times longer than dactylus. Propodus length 1.92 (1.85–2.04) times longer than dactylus. Carpus 6.96 (6.96–9.27) times as long as greatest width, slightly broader distally, distal margin with small excavation. Segment ratios 0.33 (0.27–0.33): 0.63 (0.54–0.63): 1.00 (2.13 [2.13–2.40] mm): 0.79 (0.77–0.79): 0.39 (0.38–0.39): 0.94 (0.94–1.10). Exopod extending to mid-apical third of merus.

Pereiopod 3 (fig. 28d, e) distinctly longer than pereiopod 2 and more slender 6.96 (6.48–7.20) mm long, 1.42 (1.22–1.44) times carapace length. Dactylus with prominent terminal claw and 10 (10–12) strong spines on medial margin (fig. 28e). Propodus 3.40 (3.40–4.13) times longer than dactylus, length 12.31 (12.31–12.47) times longer than wide with 7 (7–10) spines on inner margin. Merus with 2 (1–2) strong spine on medial margin and 1 near ventral distal margin. Segment ratios 0.48 (0.47–0.54): 1.65 (1.65–2.00): 1.00 (1.29 [1.13– 1.35] mm): 2.19 (1.88–2.22): 0.54 (0.54–0.78): – (1.75–2.04). Exopod extends to mid merus.

Pereiopod 4 (fig. 29a, b) similar to pereiopod 3, 6.83 (6.05–6.83) mm long, 1.39 (1.14–1.39) times carapace length. Dactylus with prominent terminal claw and 8 (8–12) spines on medial margin (fig. 29b). Propodus 3.36 (3.03–3.58) times longer than dactylus, length 14.00 (12.57–14.00) times longer than wide, with 11 (8–11) spines on medial margin and 1 apically on outer margin; merus with 2 strong spine on medial margin and 1 near ventral distal margin. Segment ratios 0.52 (0.52–0.63): 1.75 (1.75–2.04): 1.00 (1.28 [1.07–1.28] mm): 2.06 (2.00–2.06): 0.52 (0.52–0.58): 1.85 (1.85–2.00). Exopod extends to apical third of merus.

Pereiopod 5 (fig. 29c, d) similar length to pereiopod 4, 7.08 (6.48–7.08) mm long, 1.44 (1.22–1.44) times carapace length. Dactylus with prominent terminal claw and very regular, comb-like row of numerous 72 (70–80) small spines on medial margin (fig. 29d). Propodus 2.90 (2.59–3.00) times longer than dactylus, length 13.13 (12.94–13.13) times longer than wide, with 8 (8–9) long medial teeth and external margin without teeth. Carpus without any large spines near distal margin. Merus with 1 strong medial spine and 1 distal spine; ischium one-third length of propodus; segment ratios 0.71 (0.67–0.78): 2.05 (1.93–2.16): 1.00 (1.28 [1.20–1.43] mm): 1.67 (1.67–1.83): 0.81 (0.67–0.81): 1.61 (1.50–1.67). Exopod extends to mid third of merus.

Abdomen. Pleopods peduncle of first pleopod short, 0.41 (0.29–0.41) times length of carapace length, 2.67 (2.38–3.00) times width, exopod 1.25 (1.25–1.42) times peduncle length, endopod – (0.60) times peduncle length (fig. 29g); second pleopod peduncle short, 0.45 (0.38–0.55) times length of carapace, 2.93 (1.60–3.93) times width, exopod 1.14 (0.84– 1.23) times peduncle length, endopod slightly shorter – (0.80–1.13) times peduncle length. Length of first peduncle 1.10 (1.10–1.83) times length of second peduncle.

Telson (fig. 29e, f) length 3.50 (3.50–3.75) mm, 0.71 (0.66– 0.71) times carapace length and tapering distally, 3.24 (2.50– 3.48) times as long as greatest width. Dorsal surface with 2 (2–3) pairs of strong submarginal teeth-like spines. Posterior margin convex with 1 pair of teeth-like spines outermost, 12 (8–12) long strong setose terminal spines (fig. 29f).

Uropods approximately equal to telson length.

Male smaller than females, carapace length 3.88 mm; endopod of pereiopod 1 not strongly excavated with 8 short spines on outer margin, 2 spines at apex of finger-like projection and a long spine at base of projection, inner margin with 10 long setae (fig. 29h, i).

Etymology: This species is named after Dr Jean Roux, who in 1926 clearly recorded the characteristics that are diagnostic for P. rouxi from North Yanco in New South Wales. Roux also recognised a second morphological form of Paratya at the same location, similar to specimens from the Sydney area. Roux was not prepared to describe a new species based on the rostral characters, especially as similar morphology was present in the area of the type for P. australiensis . The second morphological form was probably P. arrostra .

Comments: P. rouxi can be confused with P. arrostra (4C) because both have a short rostrum, but P.rouxi lacks post-orbital spines, has 1–2 ventral rostral spines, telson 0.66–0.70 times carapace length, rostral length 0.57–0.73 times scaphocerite length, pereiopod 1 has a long slender carpus and chelae with carpus length 2.33–3.00 times longer than wide, pereiopod 2 with dactylus 0.27–0.33 times carpus length and propodus 0.54– 0.63 times carpus length and propodus 3.63–4.00 times longer than wide, whereas P. arrostra (4C) has 0–1 post-orbital spines, 4–5 ventral spines, telson 0.44–0.60 carapace length, rostral length 0.80–0.90 times scaphocerite length, pereiopod 1 has a short carpus and robust, broad cheliped with carpus length 1.71– 1.91 times longer than wide, pereiopod 2 with dactylus 0.45–0.53 times carpus length and propodus 0.74–0.79 times carpus length and propodus 2.98–3.08 times longer than wide (see Table 3).

The distribution of P. rouxi , which is found in streams in the Murray Darling Basin in New South Wales, does not overlap the short rostrum P. arrostra (4C), which occurs in the Conondale Ranges south-eastern Queensland and in the St George district in the upper Condamine R catchment, Queensland ( Calman, 1926).

Figures

Figure 27. Paratya rouxi sp. nov.: a, head region and rostrum; b, antenna 1 peduncleand stylocerite; c, scaphocerite; d, left mandible; e, enlarged incisors; f, right mandible; g, enlarged incisors; h, maxilla 1; i, maxilla 2; j, maxilliped 1; k, maxilliped 2. Scale lines 0.2 mm.

Figure 28. Paratya rouxi sp. nov.: a, maxilliped 3; b, pereiopod 1; c, pereiopod 2; d, pereiopod 3; e, dactylus 3. Scale lines 0.2 mm.

Figure 29. Paratya rouxi sp. nov.: a, pereiopod 4; b, dactylus 4; c, pereiopod 5; d, dactylus 5; e, telson; f, telson terminal spines; g, pleopod 1 of female; h, pleopod 1 of male; i, endopod 1 of male. Scale lines 0.2 mm.