Paratya williamsi, 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 : 82-87

Paratya williamsi n. sp.

Figures 15–17

http://zoobank.org/urn:lsid:zoobank.org:act:F299988B-DF09-

4765-A01E-B28875339C5D

Lineage 5 ( Cook et al., 2006)

Type Material: Holotype New South Wales. Kangaroo R Hampden Bridge , − 34.7272 S, 150.5218 E, 26 September 2017 ( PS, JM, JH). Body in ethanol and antennae, mouthparts, pereiopods and abdominal structures dissected, mounted on 2 slides. AM Ref No. P. 105603.001; Accession Ref. PS103 , Genbank Registration OL 420884.

Paratypes: New South Wales. Kangaroo R Hampden Bridge, − 34.7272 S, 150.5218 E, 26 September 2017 ( PS, JM, JH) Accession Ref. PS98 , AM Ref No. P. 105.603, Kangaroo Valley R on Gerringong Ck Rd, − 34.6868 S, 150.6013E, Accession Ref. PS99 , AM Ref No. P. 105603, 27 September 2017 ( PS, JM, JH), bodies in ethanol and other structures dissected, mounted on 2 slides each .

Material Examined: New South Wales: Hampden Bridge, − 34.7272 S, 150.5218 E, 26 September 2017 ( PS, JM, JH); Kangaroo Valley R on Gerringong Ck Rd , − 34.6868 S, 150.6013 E, 27 September 2017 ( PS, JM, JH) .

Diagnosis: Paratya williamsi differs from all other species by the following combination of characters: rostrum long, 4.80– 5.20 mm, extending beyond antennular peduncle and to end of scaphocerite, rostral length 0.84–1.03 times longer than carapace, dorsal edge curved upwards to tip, narrow and pointed, rostrum 7.16–9.60 times longer than wide, dorsally armed with 21–27 teeth, ratio of rostral spines to rostral length is 4.38–5.38, with 2–3 postorbital spines; ventrally with 1–5 short serrations over a length of 0.10–2.00 mm, 1 spine posterior to greatest depth, distal half of ventral edge straight, ratio of ventral spine length to rostral length is 0.21–1.00 and 4.40–21.00 more dorsal spines than ventral spines; rostral length 1.15–1.34 times length of scaphocerite. Left mandible with 4–5 teeth separated by a notch from 3 less distinct apical teeth; spine row immediately below incisor process of 4–6 rugose spines (lifting spines); right mandible with 4 teeth in a single incisor process with apical and fourth teeth largest separated by 2 smaller teeth. Maxilla 2 with scaphognathite truncated distally, not extending to apex of upper endite. Chelae of pereiopod 1 short and broad, 1.40–1.51 mm long, propodus 2.28–3.02 times as long as wide, 1.87–1.97 times longer than dactylus, 1.27–1.44 times longer than carpus; palm length 1.36–1.70 times longer than wide and 1.00–1.27 times longer than dactylus length. Carpus very short 2.10–2.33 times as long as greatest width. Dactylus of pereiopod 3 with prominent terminal claw and 5–7 strong spines on medial margin. Dactylus of pereiopod 4 with prominent terminal claw and 5–6 spines on medial margin.

Carapace length 5.40 (4.85–6.00) mm.

Rostrum long, 5.40 (4.80–5.20) mm, extending beyond antennular peduncle and to end of scaphocerite (fig. 15a), rostral length 0.96 (0.84–1.03) times longer than carapace, dorsal edge curved upwards to tip, narrow and pointed, rostrum 8.00 (7.16–9.60) times longer than wide, dorsally armed with 24 (21–27) teeth, ratio of rostral spines to rostral length is 4.61 (4.38–5.38), with 2 (2–3) postorbital spines (fig. 15a); ventrally with 3 (1–5) short serrations over a length of 1.50 (0.10–2.00) mm, 1 spine at greatest depth (fig. 15a), distal half of ventral edge straight, ratio of ventral spine length to rostral length is 0.29 (0.21–1.00) and 8.00 (3.50–21.00) more dorsal spines than ventral spines; rostral length 1.27 (1.15– 1.34) times length of scaphocerite.

Antenna 1 (fig. 15b) peduncle 2.75 (2.25–2.75) mm long, not reaching distal tip of scaphocerite, 0.90 (0.90–1.00) times length of scaphocerite. Stylocerite 2.25 (2.05–2.30) mm long, length 7.50 (6.83–9.20) longer than wide, 0.42 (0.38–0.45) times carapace length, reaching beyond distal border of peduncle segment but not to end of broad acute process on distal angle of first segment (fig. 15b).

Antenna 2 (fig. 15c) second segment of peduncle 1.50 (1.26–1.50) mm long, 0.37 (0.29–0.37) length of scaphocerite, 2.73 (2.29–2.73) longer than wide. Scaphocerite 4.10 (3.75– 4.35) mm long, 0.76 (0.73–0.82) times length of carapace, 3.28 (3.13–3.48) longer than wide.

Mouthparts. Left mandible (fig. 15d, e) with 4–5 teeth separated by a notch from 3 less distinct apical teeth; spine row immediately below incisor process of 4–6 rugose spines (lifting spines); spine row above molar process of approximately over 20 sparsely setose spines. Right mandible (fig. 15f, g) with 4 teeth in a single incisor process with apical and third teeth largest with second and fourth teeth smaller; spine row immediately below teeth with 8–11 lifting spines; spine row above molar process. Molar process ridged.

Maxilla 1 as for P. australiensis (fig. 15h).

Maxilla 2 (fig. 15i) scaphognathite truncated distally, not extending to apex of upper endite; palps small, terminal parts narrow and with 1 sub–apical setose spine.

Maxilliped 1 as for P. australiensis (fig. 15j).

Maxilliped 2 (fig. 15k) endopod length 0.88 (0.88–1.11) mm; exopod long and narrow 2.15 (2.00–2.50) mm, exopod 2.44 (2.27–2.46) times longer than endopodite. Epipodite with podobranch.

Maxilliped 3 (fig. 16a) endopod length 6.10 (5.68–6.27) mm, 2.71 (2.32–2.71) times longer than exopod; with 3 distal segments of similar length; basal segment curved, apical segment with large terminal claw, medial distal margin with 8 (6–8) broad teeth-like spines, largest 1 in basal third, outer margin with 7 teeth-like spines. Exopod long and narrow, 2.25 (2.25–2.70) mm long, tip reaching basal third of mid segment, with several long setose spines near tip and several short setose spines near base. Epipodite with basal conical projection.

Thoracic appendages. Pereiopod 1 (fig. 16b) 4.65 (4.65– 4.73) mm long, 0.86 (0.78–0.98) times carapace length. Chelae short and broad (fig. 16b), 1.40 (1.40–1.51) mm long, propodus 2.54 (2.28–3.02) times as long as wide, 1.87 (1.87–1.97) times longer than dactylus, 1.27 (1.27–1.44) times longer than carpus; palm length 1.36 (1.36–1.70) times longer than wide and equal to dactylus length (1.00–1.27). Carpus very short 2.20 (2.10–2.33) times as long as greatest width, broadening distally, distal margin excavate. Segment ratios 0.68 (0.68– 0.76): 1.27 (1.27–1.44): 1.00 (1.10 [1.05–1.10] mm): 1.50 (1.43–1.52): 0.45 (0.45–0.57): 1.27 (1.27–2.71). Exopod extending to mid merus (mid merus to mid carpus).

Pereiopod 2 (fig. 16c) 6.20 (5.80–7.50) mm long, 1.15 (1.15–1.25) times carapace length. Chelae long and slender (fig. 16c), 1.50 (1.35–1.50) mm long, nearly two-thirds length of carpus, 2.33 (2.25–3.33) times longer than wide, palm length 1.56 (1.50–1.56) times longer than width and 0.82 (0.82–1.20) times dactylus length. Propodus length 1.76 (1.76–1.80) times longer than dactylus. Carpus 5.71 (5.14– 8.33) times as long as greatest width, slightly broader distally, distal margin with small excavation. Segment ratios 0.43 (0.34–0.43): 0.75 (0.60–0.75): 1.00 (2.00 [1.80–2.50] mm): 0.68 (0.68–0.80): 0.68 (0.60–0.75): 1.50 (1.24–1.50). Exopod extending to apex of merus to base of carpus.

Pereiopod 3 (fig. 16d, e) distinctly longer than pereiopod 2 and more slender 8.45 (7.65–9.15) mm long, 1.56 (1.53–1.58) times carapace length. Dactylus with prominent terminal claw and 5 (5–7) strong spines on medial margin (fig. 16e). Propodus length 4.58 (4.46–4.58) times longer than dactylus, length 11.00 (10.00–14.50) times longer than wide with 13 (11–13) spines on inner margin. Merus with 1–3 strong spines on medial margin and 1 near ventral distal margin; segment ratios 0.40 (0.37–0.40): 1.83 (1.67–1.83): 1.00 (1.50 [1.50–1.65] mm): 2.13 (2.03–2.13): 0.67 (0.40–0.67): 1.53 (1.53–1.88). Exopod extends to mid merus (mid merus to apex of merus).

Pereiopod 4 (fig. 17a, b) similar to pereiopod 3, 7.80 (7.45– 9.63) mm long, 1.44 (1.34–1.54) times carapace length. Dactylus with prominent terminal claw and 5 (5–6) spines on medial margin (fig. 17b). Propodus length 5.40 (4.75–5.40) times longer than dactylus, length 10.80 (10.00–11.40) times longer than wide, with 11 (8–13) spines on inner margin; merus with 0–2 strong spines on medial margin and 1 near ventral distal margin. Segment ratios 0.36 (0.36–0.40): 1.93 (1.79– 1.93): 1.00 (1.40 [1.40–1.50] mm): 1.93 (1.80–2.04): 0.71 (0.50–0.71): 1.71 (1.61–1.71). Exopod extends to mid merus.

Pereiopod 5 (fig. 17c, d) slightly shorter than pereiopods 4, 7.65 (7.20–8.30) mm long, 1.42 (1.38–1.48) times longer than carapace. Dactylus with prominent terminal claw and very regular, comb-like row of 50 (49–66) spines on medial margin (fig. 17d). Propodus length 4.07 (3.93–4.07) times longer than dactylus, length 14.25 (11.00–14.25) times longer than wide with 7 (7–10) long inner teeth and setae on external margin. Carpus with 1 large spines near distal margin. Merus with 1 strong medial spine and 1 distal spine; segment ratios 0.50 (0.47–0.56): 2.04 (1.91–2.20): 1.00 (1.40 [1.25–1.60] mm): 1.71 (1.50–1.92): 0.71 (0.64–0.78): 1.43 (1.31–1.43). Exopod extends to base to third of merus.

Abdomen. Pleopods peduncle of first pleopod short 1.90 (1.50–2.35) mm, 0.35 (0.31–0.39) times length of carapace length, 2.92 (2.92–5.85) times width, exopod 1.08 (1.08–1.28) times peduncle length, endopod 0.60 (0.45–0.80) times peduncle length (fig. 17g); second pleopod peduncle short, 0.42 (0.36–0.45) times length of carapace, 2.50 (2.33–2.81) times width, exopod 1.16 (–) times peduncle length, endopod slightly shorter 1.04 (–) times peduncle length (fig. 17h).

Telson (fig. 17e, f) length 3.50 (3.50–4.00) mm, 0.65 (0.67–0.72) times carapace length, 3.04 (2.81–3.17) times as long as greatest width, tapering distally. Dorsal surface with 2 pairs of strong submarginal teeth-like spines. Posterior margin convex with 1 pair of teeth-like spines outermost, 6 (6–8) long, strong terminal setose spines (fig. 17f).

Uropods approximately equal to telson length.

Male smaller than female, carapace length 4.7mm; endopod of pleopod 1 strongly excavated and strongly curved (fig. 17i, j) with 11 short spines on outer margin and 12 long setae on inner margin (fig. 17j).

Etymology: The specific epithet is in honour of the late Prof. W. D. Williams who encouraged and inspired a generation of Australian limnologists and who provided one of us (PS) a unique opportunity for post-graduate study at Adelaide University.

Comments: P. williamsi has an overlap of distribution with P. australiensis and P. arrostra . Characters that distinguish these species from P. williamsi are listed in Table 2.

P. williamsi may also be confused with P. whitemae and P. tasmaniensis , both of which are widespread and may have distributions that overlap, but they can be distinguished by the following combination of characters: dactylus of pereiopod 3 with 5–7 teeth; dactylus of pereiopod 4 with 5–6 teeth; dactylus of pereiopod 5 with a comb of 49–74 spines; first cheliped palm length 1.00–1.27 times dactylus length; 1–5 ventral rostral spines over a length of 0.10–2.00 mm ( Table 2).

P. williamsi is restricted to the upper Kangaroo Valley in the Shoalhaven R catchment south of Sydney and can be found co-existing with P. whitemae and P. tasmaniensis .

Figures

Figure 15. Paratya williamsi sp. nov.: a, head region and rostrum; b, antenna 1 peduncle and 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 16. Paratya williamsi sp. nov.: a, maxilliped 3; b, pereiopod 1; c, pereiopod 2; d, pereiopod 3; e, dactylus 3. Scale lines 0.2 mm.

Figure 17. Paratya williamsi 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 2 of female; i, pleopod 1 of male; j, endopod 1 of male. Scale lines 0.2 mm.