Platymamersopsis (s. str.) spinalis, Goldschmidt, 2008

Goldschmidt, Tom, 2008, Taxonomical, ecological and zoogeographical studies on anisitsiellid water mites (Acari: Hydrachnidia: Anisitsiellidae Koenike, 1910) from Madagascar, Zootaxa 1954 (1), pp. 1-120 : 106-108

Platymamersopsis (s. str.) spinalis sp. nov.

( Figs 257–263 , Table 12)

Type: Holotype female, MD 61 , Tsimelahy (Tulear), lake (formed by Rivière Antanrantsa), 200 m asl, 21.0 °C (surface 25.8 °C), 220 µS/cm, 05.09.2001, mounted.

Additional material examined: MD 78 a, Fort Dauphin (Tulear), Mandena ( QMM area), Rivière Amendano 0.5 km upstream road bridge, riffle, 12 m asl, 15.09.2001, 1/1/0 mounted ; MD 78 b, Fort Dauphin (Tulear), Mandena ( QMM area), Rivière Amendano 0.5 km upstream road bridge, pool, 12 m asl, 15.09.2001, 1/0/0 mounted ; MD 122 a, Maromandia (Majunga), Rivière Manongarivo, dead wood, 60 m asl, 30.5 °C, 42 µS/cm, 22.10.2001, 1/0/0 mounted .

Habitat: Large, slow flowing lowland rivers at 12–200 m asl.

Distribution: Madagascar (Southern and Northern lowland).

Derivatio nominis: Spina (Latin) — thorn, spine; referring to the long, spine-like terminal setae on leg- IV-6.

Diagnosis: Idiosoma small, rounded-oval; ridge on dorsal shield apically pointed, caudally dissolved; dorsal shield anteriorly truncated; coxal field relatively short, medial margins of Cx-I and Cx-III mid-sized; genital field broad rectangular, caudally surpassing genital bay; acetabula mid-sized, oval; legs moderately compact, claws on leg-I to -III strong, with single dorsal clawlet and comb-like ventral clawlets; leg-IV-6 with two long terminal setae and several strong, long sub-terminal setae; capitulum compact; palp relatively stout, ventral margin of P2 slightly concave, dorsal margin rounded.

Description, female (n = 2): Idiosoma rounded-oval ( Fig. 257 ), grey-bluish, secondary sclerotization light brown-greyish; dorsal shield oval to broad drop-shaped (L/W 461 (486)/353 (373)), ridge on dorsal shield apically pointed, caudally dissolved, glandularia far laterally, Dgl-3 to -5 with stronger setae, Dgl-6 and Lgl-4 far peripheral, with smaller setae; soft integument in dorsal furrow lined ( Fig. 258 ); ventral shield rounded-oval (L/W 510 (523)/402 (412)); coxal field relatively short, broad, Cx-I to -III relatively small, anteriorly only slightly surpassing ventral shield; medial margin Cx-I (45 (51)) and Cx-III (32 (27)) mid-sized ( Fig. 257 ); Cxgl-2 at posterior margin of Cx-II, relatively far laterally, Cxgl-4 close to anterior margin of Cx- III; Cx-IV caudally bluntly pointed, medial margin passing with rectangular corner to straight caudo-lateral margin, laterally rounded, dorso-laterally extended up to dorsal of Cx-III ( Fig. 257 ), lateral ridge approximately straight ( Fig. 257 ); genital field large, broad-rectangular (L/W 120 (125)/120 (120)), anteriorly and posteriorly rounded, laterally smoothly convex, caudally clearly extended beyond genital bay; acetabula midsized, oval (Ac1 and Ac3 far remote from anterior and posterior end of genital flaps respectively), setae on genital flaps small ( Fig. 257 ); setae of Vgl-1 posterior to caudal corner of Cx-IV, Vgl-3 closer to caudo-lateral margin of Cx-IV; excretory pore and Vgl-2 relatively close together, glandularia close to caudal margin of ventral shield; legs moderately compact, leg-I to -III with several strong, pointed setae, claws heavy with single, strong dorsal clawlet and comb-like ventral clawlets ( Fig. 259 ); leg-IV relatively slender, with many heavy setae, terminal segment slender, with two long terminal setae and a row of four stronger sub-terminal setae ( Fig. 260 ); capitulum short, with short rostrum, dorsal apodemes slender, ventral margin proximally inflated, towards rostral concave ( Fig. 261 ); chelicera typical; palp compact, strong; P2 short, compact, with four dorsal and two latero-dorsal setae, dorsal margin curved; ventral margin slightly concave ( Fig. 261 ), ventral seta mid-sized, pointed; P3 with two dorso-medial and one lateral setae; P4 with ventro-distal protrusions, ventral setae distally; P5 compact ( Fig. 261 ).

Male (n = 3): Idiosoma ( Figs 262, 263 ) smaller than in females (L/W, dorsal shield 397–422/304–314, ventral shield 441–466/343–363); genital field smaller, more rounded (L/W 86–88/83–86) ( Fig. 262 ); legs and gnathosoma similar to females.

Remarks: The three Malagasy representatives of the mysorensis –like species group ( Platymamersopsis (s. str.) davecooki , P. palustris and P. spinalis ) are distinct from all African, as well as the other Malagasy species, due to their comb-like ventral clawlets on the claws of leg-I to -III. They share this character with the two Indian species P. adhika Cook, 1967 and P. mysorensis Cook, 1967 . Within these species, Platymamersopsis (s. str.) palustris is characterised by a relatively large, rounded idiosoma and very short coxal field, not protruding over the ventral shield; furthermore, the ventral margin of P2 is slightly convex, whereas it is straight or concave in the other species and the central ridge on the dorsal shield is only developed as an anterior and lateral arch. The legs-I to -III of Platymamersopsis (s. str.) palustris are slenderer than in P. (s. str.) spinalis and P. (s. str.) davecooki , and the terminal setae of leg-IV-6 are shorter than in the latter species. In Platymamersopsis (s. str.) spinalis the coxal field is shorter than in the two Indian species (especially the medial margin of Cx-I and Cx-III). The species is separated from Platymamersopsis (s. str.) palustris and P. (s. str.) davecooki by the very long terminal and sub-terminal setae on leg-IV-6. Platymamersopsis (s. str.) davecooki is characterised by an anteriorly very broad and rounded dorsal shield, a very small genital field (in both sexes) and straight ventral margin of P2.

Figures

FIGURES 257–261. Platymamersopsis spinalis sp. nov., female holotype (MD 61): 257, idiosoma, ventral view; 258, idiosoma, dorsal view; 259, leg-II; 260, leg-IV; 261, capitulum with left palp and chelicera, lateral view. Scale bars = 100 µm.

FIGURES 262, 263. Platymamersopsis spinalis sp. nov., male (MD 78a): 262, idiosoma, ventral view; 263, idiosoma, dorsal view. Scale bar = 100 µm.