Floresorchestia pongrati, Suklom & Keetapithchayakul & Abdul Rahim & Wongkamhaeng, 2022

Suklom, Anotai, Keetapithchayakul, Tosaphol Saetung, Abdul Rahim, Azman & Wongkamhaeng, Koraon, 2022, Two new species of the genus Floresorchestia (Crustacea, Amphipoda, Talitridae) from Amphawa Estuary, Samut Songkhram Province, Thailand, Zoosystematics and Evolution 98 (2), pp. 285-303 : 285

Floresorchestia pongrati sp. nov.

Type material.

Holotype. ♂, 10 mm, THNHM-lv-19369, THAILAND, Amphawa District, Samut Songkhram, Thailand (13°26'03.8"N, 100°00'36.2"E), 10 April 2021, Piyangkun Lueangjaroenkit; THNHM-lv-19370, Paratype, 1 ♂ and 5 ♀ collected with holotype.

Type locality.

Moist area near Mae Klong Canal banks, (13°26'03.8"N, 100°00'36.2"E), Muang Samut Songkhram District, Samut Songkhram, Thailand.

Habitat.

Riparian-hoppers living in the moist area near Mae Klong canal banks of Amphawa District, Samut Songkhram, Thailand.

Etymology.

The species is named in honour of Assistant Professor Pongrat Dumrongrojwattana from Burapha University, Thailand for his contribution on terrestrial Floresorchestiinae diversity in Thailand.

Ecological type.

Riparian-hoppers (edges of lakes under stones or in very wet vegetation, near (or in) streams, rivers, creeks, cascades and waterfalls).

Description.

Based on holotype, male, 10 mm, THNHM-lv-19369.

Head. (Fig. 3FP ) Eye medium (1/3 the length of the head). Antenna 1 (Fig. 9A1 ) short, rarely longer than article 4 of antenna 2 peduncle. Antenna 2 (Fig. 9A2 ) shorter than half body length; articles slender, article 5 longer than article 4; flagellum with 18 articles, final article cone-shaped with an apical cluster of setae.

Upper lip (Fig. 10UL ) broad, deep, apex rounded, without robust setae. Lower lip (Fig. 10LL ) present; without inner plates. Left Mandible (Fig. 10LMD ) incisor 6-dentate; left lacinia mobilis 5-dentate and four plumose setae in one row; molar strong with 28 striations and one plumose seta. Right mandible (Fig. 10RMD ) incisor 5-dentate; lacinia mobilis with numerous dents, three robust setae and cluster of fine setae; molar strong with 22 striations and one plumose seta. Maxilla 1 (Fig. 10MX1 ) inner plate slender with two terminals plumose setae; the outer plate with eight robust serrated setae, with small 1-articulate palp. Maxilla 2 (Fig. 10MX2 ) plates narrow, inner plate slightly shorter than outer; inner plate with 16 subapical robust setae, one plumose seta and seven facial setae; outer plate with 26 apical robust setae in two rows. Maxilliped (Fig. 10MP ) inner plate apical and subapical with plumose setae, robust setae and two large conical robust setae; outer plate with two rows subapical setae and plumose setae; palp article 2 distomedial lobe well developed with numerous setae; article 4 reduced, button-shaped.

Pereon. Gnathopod 1 (Fig. 9G1 ) sexually dimorphic; sub-chelate, coxa smaller than coxa 2, ventral margin lined with five robust setae, anterior margin straight; basis slightly expanded, anterior margin with five setae, posterodistal margin with two setae; posterior of merus, carpus and propodus each with lobe covered in palmate setae; carpus longer by 1.2 × than propodus, anterior margin with one robust seta and three distal robust setae, posterior margin with three robust setae; propodus subtriangular with well-developed posterior lobe, anterior side with five robust setae, posterior lobe with five robust setae, palm slightly serrated, lined with six robust setae; dactylus cuspidactylate, shorter than palm, with two robust setae.

Gnathopod 2 (Fig. 9G1 ) sexually dimorphic; subchelate; coxa anterior margin with 13 robust setae; basis anterior margin smooth, slightly expanded, posterior margin with four robust setae; ischium with rounded lobe on anterior margin; posterior of merus, carpus and propodus without lobe covered in palmate setae; carpus triangular, reduced, enclosed by merus and propodus, posterior lobe absent; propodus subovate, 1.4 × as long as wide, palm reaching about 30%, posteromedial surface of propodus with groove, anterior side naked, palm lined with 19 robust setae; dactylus longer than palm fitted with facial groove, attenuated distally, inner margin lined with 11 robust setae.

Pereopod 3 (Fig. 11P3 ) coxa longer than broad with posterior process, anterior margin with nine robust setae; basis slightly expanded, anterior margin with four robust setae and posterior margin with four robust setae, with two posterodistal robust setae; ischium shortest; anterior and posterior margin of merus lined with four clusters of robust setae; carpus and propodus slightly expanded; carpus posterior margin with three cluster of robust setae; propodus slender and longer than carpus; dactylus without notch on posterior margin.

Pereopod 4 (Fig. 11P4 ) slightly shorter than pereopod 3; coxa longer than broad, anterior margin with six robust setae and with small posterior process; basis longest posterior margin with five robust setae; ischium shortest, posterodistal with three robust setae; merus and carpus shorter than those of pereopod 3; merus distally expanded, longer than carpus and propodus, anterior and posterior margin with three and four clusters of robust setae, respectively; carpus shorter than propodus, posterior margin with one cluster of robust setae; propodus slender, with four clusters of robust setae in posterior side; dactylus slender and longer than that of pereopod 3, thickened proximally with a notch mid-way along posterior margin.

Pereopod 5 (Fig. 11P5 ) coxa bilobed, anterior lobe distinctly large than posterior lobe, posterior lobe with five robust setae on ventral margin; basis anterior margin with four robust setae and two anterodistal robust setae, posterior margin with serrate and small setae; merus and carpus distally expanded; carpus shorter than propodus; propodus slender, longer than merus and carpus.

Pereopod 6 (Fig. 11P6 ) coxa bilobed, posterior lobe larger than anterior; basis expanded, anterior margin with 10 robust setae, posterior margin with row of tiny setae; ischium shortest; merus distally expanded, anterior side with four clusters of robust setae; carpus expanded less than merus, anterior margin lined with five clusters of robust setae; propodus slender, longer than merus and carpus; dactylus slender without subapical robust setae.

Pereopod 7 (Fig. 11P7 ) coxa reduced; posterior margin of basis with distinct minute serration (each serrate with small seta), anterior margin with 11 robust setae; ischium distally expanded; merus and carpus expanded; propodus longer than merus and carpus; dactylus slender with subapical robust setae.

Pleon. (Fig. 12 ) Pleopods all well developed. Pleopod 1 (Fig. 12PL1 ) peduncle without marginal setae; biramous, outer ramus shorter than peduncle; inner ramus with 13 articles; outer ramus with 10 articles, first article lined with four plumose setae. Pleopod 2 (Fig. 12PL2 ) peduncle without marginal setae; biramous, outer ramus shorter than peduncle, inner ramus subequal to outer ramus, shorter than peduncle; inner ramus with 10 articles; outer ramus with 12 articles. Pleopod 3 (Fig. 12PL3 ) peduncle without marginal setae; biramous, inner ramus subequal to outer ramus, shorter than peduncle; inner ramus with 11 articles; outer ramus 10 articles, first article lined with five plumose setae, shorter than peduncle.

Epimera (Fig. 12EP ), epimeron 1 posterodistal corner slightly protrudes, without slit. Epimera 2 and 3 each with slits above ventral margin with 27 and 29 slits, respectively. Epimeron 3 posteroventral corner and ventral margin smooth.

Uropod 1 (Fig. 12U1 ) peduncle with six robust setae in one row; inner ramus subequal in length to outer ramus, inner ramus with marginal five robust setae in one row, apical with four robust setae; outer ramus without marginal robust setae, apical with four robust setae. Uropod 2 (Fig. 12U2 ) peduncle with five robust setae; inner ramus subequal in length to outer ramus; inner ramus with four marginal robust setae, apical with three robust setae; outer ramus with two marginal robust setae, apical with three robust setae. Uropod 3 (Fig. 12U3 ) uniramous, peduncle with one robust seta; ramus shorter than peduncle, with one marginal robust seta and three apical robust setae.

Telson (Fig. 12TL ) longer than broad, weakly cleft, dorsal mid-line at less than halfway, with four marginal and three apical robust setae.

Female (Sexually dimorphic characters) (Fig. 13 ). Type. Paratype, female, 8.5 mm, THNHM-lv-19370.

Pereon. Gnathopod 1 (Fig. 13G1 ) merus lacking tumescent lobe, posterior margin with five robust setae; propodus without tumescent protuberance, anterior margin with two robust setae, posterior margin with three clusters of robust setae; palm slightly transverse, dactylus inner lateral posterior margin with five robust setae.

Gnathopod 2 (Fig. 13G2 ) mitten-shaped; posterior margin of carpus and propodus each with lobe covered in palmate setae; carpus well developed, posterior lobe projecting between merus and propodus; nearly twice as long as wide; palm obtuse, lined with 10 robust setae, posterodistal corner with two robust setae; dactylus not modified distally, blunt.

Telson (Fig. 13TL ) as broad as long, weakly cleft, dorsal mid-line less than halfway, with two marginal and three apical robust setae.

Remarks.

Floresorchestia pongrati sp. nov. is closely similar to F. papeari which has synapomorphic character states such as: (1) left mandible lacinia mobilis 5-dentate; (2) gnathopod 2 dactylus posterior margin smooth; (3) gnathopod 1 carpus significantly longer (1.2 ×) than propodus; (4) gnathopod 2 propodus (1.4 ×) as long as wide; (5) uropod 3 ramus with marginal setae; (6) telson longer than broad and (7) epimera 2-3 with slits. They are distinguished by the following [characters of F. papeari in brackets]: 1) antenna 2 less than half body length [shorter than head and first three pereonites]; (2) gnathopod 2 dactylus posterior margin smooth, proximal tooth absent [with proximal tooth]; (3) gnathopod 2 distally acute or attenuated [not modified distally, blunt]; (4) gnathopod 2 palm without protuberance near dactylar hinge [with rounded protuberance near dactylar hinge]; (5) uropod 1 inner ramus with five marginal setae [four marginal setae]; (6) uropod 3 peduncle with one robust seta [five robust setae]; (7) telson with seven robust setae per lobe [five robust setae per lobe].

Figures

Figure 3. Male habitus of Floresorchestia spp. FA. F. amphawaensis sp. nov. holotype, male, 7.8 mm (THNHM-lv- 18763), Amphawa District, Samut Songkhram, Thailand; FP. F. pongrati sp. nov. holotype, male, 10 mm (THNHM-lv- 19369), Amphawa District, Samut Songkhram, Thailand. Scale bars: 1 mm (FA, FP).

Figure 9. Floresorchestia pongrati sp. nov. holotype. Scale bars: 0.25 mm (A 1, A 2, G 2); 0.5 mm (G 1).

Figure 10. Floresorchestia pongrati sp. nov. holotype. Scale bars: 0.1 mm (LL, LMD, MP, MX 1, MX 2, RMD, UL).

Figure 11. Floresorchestia pongrati sp. nov. holotype. Scale bars: 0.25 mm (P 3 - P 7).

Figure 12. Floresorchestia pongrati sp. nov. holotype. Scale bars: 0.1 mm (TL, U 1 - U 3); 0.2 mm (PL 1 - PL 3, EP).

Figure 13. Floresorchestia pongrati sp. nov. paratype, female 8.5 mm (THNHM-Iv- 19370 Amphawa District, Samut Songkhram, Thailand. Scale bars: 0.1 mm (TL); 0.25 mm (G 1, G 2); 1 mm for habitus.