Hydrodroma novacaledonica Pešić & Smit, 2021

Pešić, Vladimir, Smit, Harry & Mary, Nathalie J., 2021, Two new water mite species of the genus Hydrodroma Koch, 1837 from New Caledonia (Acari, Hydrachnidia: Hydrodromidae), Acarologia 61 (3), pp. 581-590 : 582-585

Hydrodroma novacaledonica Pešić & Smit sp. nov.

Zoobank: C2A308F0-C3CB-4A75-AE55-D113163B5A91

Figs. 1 A-C, E-G

Synonym — Hydrodroma kakadu Pešić & Smit 2007a: 38 [in part].

Material examined — Holotype ♂ ( MNHN), New Caledonia, Creek des Japonais at crossing with road Thio-Boulouparis, 27 Sept. 2000, leg. Smit, dissected and slide mounted . Paratypes: 2♂, 3♀, same place and data as holotype, 1♀ dissected and slide mounted ( MNHN, RMNH); 8♀, 1 deutonymph, New Caledonia, Hienghène Rivière, 19 km from mouth, 29 Sept. 2000, leg. Smit ( RMNH).

Other material — New Caledonia: Rivière Amoa tributary RG, 20°58 ′ 47.857 S,

165°09 ′ 32.126 E, 25 Oct. 2005 leg. Flouhr, 1♂, 1♀ ; Rivière Nodéla, 20°26 ′ 42.600

S, 165°19 ′ 52.345 E, 13 May 2005 leg. Flouhr, 1♀ ; Rivière Nodéla, 20°26 ′ 42.600 S,

165°19 ′ 52.345 E, 13 May 2005 leg. Flouhr, 1♀ ; Dothio Rivière at crossing with road Thio- Nakéty, 28.ix.2000, leg. Smit, 4♀ ; Oua Mendiou Rivière 30 km from mouth, 01 Oct. 2000, leg. Smit, 3♀ ; Thio Rivière at crossing with road to Kouaré, 27.Sept. 2000 leg. Smit, 1♂ ; Rivière Coulée, 22°10 ′ 24.327 ″ S, 166°37 ′ 18.119 ″ E, 21 Oct. 2005 leg. Smit, 1♂, 2♀ ; Rivière Coulée, 22°60 ′ 25.876 ″ S, 166°37 ′ 22.857 ″ E, 20 Sept. 2001 leg. Mary, 1♀ [damaged; gnathosoma and palps lacking]; Rivière Thio, 21°38 ′ 13.4736 ″ S, 166°11 ′ 56.935 ″ E, 29 Oct. 1997 leg. Mary,

1♀, dissected and slide mounted ( RMNH); Thio 7, 02.viii.2000 leg. Mary, 2♀ ; Néaoua, 27 Oct. 1999, leg. Mary, 1♀ ; Thiiem, 02 Nov. 1999 leg. Mary, 5♀ ; Boghen 1, 30 Oct. 1999, leg.

Mary, 1♀ ; Thio 7 (Dothio I), 12 Jan. 2000 leg. Mary, 2♀.

Diagnosis — Idiosoma and gnathosoma large in size (idiosoma L ˃ 1000, genital plates

L ˃ 200, P-4 ˃ 190 µm); integument papillae rounded. Genital plates with 47–51 pairs of Ac in at most 4 longitudinal rows. Leg setae numbers: II-L-posterior 3-4; III-L-4 posterior 9-14; III-L-5 posterior 7-11; IV-L-4 anterior 8-12, posterior 9-14; IV-L-5 anterior 0, posterior 6-8.

Description — Integument with reticulation in deeper layers ( Fig. 4B ). Cx-I+II medially separated by a fine membranous line, with a row of long fine setae at medial margins of Cx-I, and posterior margins of Cx-II, -III, and -IV. Genital flaps with rounded lateral and concave medial margins. Excretory pore sclerotized. Leg claws without claw blade, with a dorsal clawlet.

Male (holotype): Idiosoma L 1300, W 1050. Coxal field L 588; Cx-III W 659, L Cx-I+II

253, Cx-III+IV 322; coxal setae numbers: Cx-I, 17; Cx-II, 19; Cx-III, 13; Cx-IV 18. Genital plate L 208, on each plate Ac number 49, with 23-26 setae, all hollow. Ejaculatory complex L

194.

Gnathosoma vL 244; chelicera total L 277, L basal segment 211, claw 63, L ratio basal segment/claw 3.3. Palp ( Fig. 1E ) total L 452, dL/H, dL/H ratio: P-1, 56/37, 1.53; P-2, 77/56, 1.38; P-3, 50/58, 0.87; P-4, 191/45, 4.3; P-5, 78/19, 4.2; L ratio P-2/P-4, 0.4. dL IV-L: 94, 169,

191, 297, 313, 275.

Female (paratype from Creek des Japonais, n = 1; in parentheses some measurements of the specimen from Rivière Thio, n = 1): Idiosoma L 1420 (1350), W 1160. Coxal field L 623 (622); Cx-III W 669 (644); L Cx-I+II 291 (283), Cx-III+IV 363 (338); coxal setae numbers:

Cx-I, 19 (16); Cx-II, 28 (19); Cx-III, 20 (15); Cx-IV 16 (17). Genital plate large, L 228 (219),

on each plate Ac number 51 (47), with 26 (22) setae.

Gnathosoma vL 255 (259); chelicera total L 309 (305), L basal segment 242 (231), claw 66 (67), L ratio basal segment/claw 3.7 (3.5). Palp ( Fig. 1F ) total L 463 (464), dL/H, dL/H ratio: P-1, 56/39, 1.44 (60/42, 1.4); P-2, 77/62, 1.25 (83/63, 1.32); P-3, 52/59, 0.87 (48/55, 0.88); P-4,

198/47, 4.2 (195/45, 4.3); P-5, 80/19, 4.1 (78/20, 3.9); L ratio P-2/P-4, 0.39 (0.42). dL IV-L:

111 (113), 184 (172), 209 (198), 325 (316), 338 (347), 292 (291).

Etymology — Named after the island where the new species was collected.

Discussion — The new species from New Caledonia closely resembles Hydrodroma kakadu Pešić & Smit, 2007 , a species similar in the presence of 3-4 swimming setae on II-L-5 and in the absence of swimming setae from anterior IV-L-5. It was originally described from Kakadu National Park, Australia, and reported also from New Caledonia ( Pešić & Smit 2007a). The latter authors mentioned that specimens of H. kakadu from Australia differ from specimens from New Caledonia, in this study assigned to the new species H. novacaledonica sp. nov., in smaller dimensions of the idiosoma and gnathosoma (e.g., idiosoma L: ˂ 800 in ♂, ˂ 1000 in ♀ ; L genital plates ˂ 180 in ♂, ˂ 190 µm in ♀ ; in both sexes L gnathosoma ˂ 190, chelicera ˂ 250, P-4 ˂ 150 µm) and in a reduced number of swimming setae on III/IV-L (less than 10 on both posterior III-L-4 and anterior IV-L-4) ( Pešić & Smit 2007a). These differences are confirmed by the examination of new material from New Caledonia. Moreover, the new species from New Caledonia differs in the shape of integument papillae (rounded vs. pointed in specimens of H. kakadu from Australia ; compare Fig. 1C and Fig. 1D ).

Distribution — New Caledonia.

Figures

Figure 1 A-C, E-G: Hydrodroma novacaledonica sp. nov. (A, E, G holotype ♂, Creek des Japonais; B-C, ♀, Creek des Japonais; F, ♀, Rivière Thio): A-B – genital field; C – integument papillae; E – palp, lateral view; F – palp, medial view; G – IV-L-6. D:H. kakadu, ♀, Plunge Pool Edith Falls, Northern Territory: integument papillae. Scale bars = 100 μm.

Figure 4 Photographs of selected parts. A-G:Hydrodroma novacaledonica sp. nov. (A, D, F, holotype ♂, Creek des Japonais; B-C, E, G, ♀, Creek des Japonais): A, C – coxal and genital field; B – dorsal integument papillae; D-E – genital field; F = ejaculatory complex; G – gnathosoma, lateral view; H-K:Hydrodroma pacifica sp. nov. (H holotype ♂, Rivière Ouénaoué; K-I ♀, La Coulée Rivière): H – ejaculatory complex; I – genital field; K – coxal and genital field. Scale bars = 100 μm.