First records of water mites from La Réunion Island with the description of one new species (Acari, Hydrachnidia) Author SmitK, Harry Naturalis Biodiversity Center, P. O. Box 9517, 2300 RA Leiden, the Netherlands. Author PešićK, Vladimir Department of Biology, University of Montenegro, Cetinjski put b. b., 81000 Podgorica, Montenegro. Author MaryK, Nathalie J. Ethyc’O, B. P. 13821, Nouméa Cedex, Nouvelle-Calédonie. & Naturalis Biodiversity Center, P. O. Box 9517, 2300 RA Leiden, the Netherlands. text Acarologia 2023 2023-10-11 63 4 1102 1108 http://dx.doi.org/10.24349/plo9-k5es journal article 10.24349/plo9-k5es 2107-7207 10785839 E9C367CC-9721-4AAC-A3A1-4A3DA2D46EB6 Diplodontus insulanus Smit & Pešić sp. nov. Zoobank: 84778292-DBC8-41BD-B3FB-7A1C394AC8A7 Figures 1-2 Material examined — Holotype ♀ , dissected and slide mounted, La Réunion , Ravine des Trois Cascades , 21.0694537°S , 55.5136127°E , 967 m asl ., 7 Oct. 2021 , leg. N. Mary ( MNHN ). Diagnosis (Female) — Idiosoma with sclerotized muscle arrangements arranged in pattern plesiotypically found in hydryphantoid mites, frontalia similar in size to pre- and postfrontalia, Table 1 Details of barcoded Neumania nodosa ( Daday, 1898 ) specimens, including data and coordinates of sampling sites, the barcode index number (N indicates a new BIN that contains only current sequences) and associated data obtained from BOLD. NN BIN = nearest neighbour BIN; NN taxonomy = species assigned to nearest neighbour BIN. For Genbank accession numbers of N. paratribreviseta see Ding et al. (2020) . Locality Coordinates Voucher Code BOLD/GenBank Acc Nos BIN BOLD NN BIN BOLD NN taxonomy Neumania nodosa ( Daday, 1898 ) La Réunion , Bras 20.9777° S , CCDB_44300_H02 HYDOC086-22/OR501727 Neumania du Bernica 55.5201° E CCDB_44300_H03 HYDOC087-22/OR501726 BOLD:AEZ7137N BOLD:AEG1862 paratribreviseta (= N. sp. 2 ZD-2020) CCDB_44300_H04 HYDOC088-22/OR501725 CCDB_44300_H05 HYDOC089-22/OR501724 Figure 1 Diplodontus insulanus Smit & Pešić sp. nov. , ♀ holotype, Ravine des Trois Cascades, La Réunion. A – idiosoma, dorsal view; B – idiosoma, ventral view; C – genital field; D – palp, medial view; E – palp, lateral view; F – gnathosoma; G – chelicera. Scale bars = 100 µm. Figure 2 Diplodontus insulanus Smit & Pešić sp. nov. , ♀ holotype, Ravine des Trois Cascades, La Réunion, IV-L. Scale bar = 100 µm. the latter developed as rounded platelets; dorsocentralia and dorsolateralia with the same diameter as glandularia; genital field with 51-55 pairs of Ac; chelicera basal segment/claw ratio 1.7; legs without swimming setae, stout, covered with numerous thick and strong setae. Description (Female) — Idiosoma with sclerotized muscle arrangement platelets ( Fig. 1A ), frontalia with a border of a secondary sclerotization, similar in size to pre- and postfrontalia, the latter developed as small, rounded platelets, dorsocentralia and dorsolateralia in the same diameter as glandularia or slightly smaller, only four pairs of dorsocentral plates present due to the fusion of the first and second dorsocentralia. Coxae with fine setae, concentrated at the distal margin of Cx-I, Cx-I+II with a rounded, medially directed projection at the posterior margin of the gnathosomal bay. Genital field with halfmoon shaped genital flaps, medially with an acetabula-free, porose area flanked by two rows of fine setae, mediocaudally with a tuft of longer setae ( Fig. 1C ). Gnathosoma with an equally S-shaped ventral margin, rostrum distinct ( Fig. 1F ); chelicera slender with a strong straight claw ( Fig. 1G ); palp setation as illustrated in Figure 1 D-E, P-2 mediodistally with a group of four to five strongly developed, apically curved setae ( Fig. 1D ). Legs with high number of uniformly thick and stout setae, scattered over the dorsal and lateral surface of segments 1-5 and arranged in dense rows at distal margins of these segments as illustrated in Fig. 2 for IV-L. Measurements — Idiosoma L 1044, W 681; coxal field: L 520; Cx-III W 597; genital field L/W 222/238, ratio 0.93, 51-55 pairs of Ac. Eggs maximum diameter (n = 3) 131-144. Chelicera total L 453, L basal segment 288, claw 166, L basal segment/claw ratio 1.73. Palp: total L 398-415; dL/H, dL/H ratio: P-1, 56/47, 1.2; P-2, 103-106/72-73, 1.4-1.5; P-3, 78/66-69, 1.13-1.19; P-4, 125-141/41, 3.1-3.5; P-5, 33-37/19-19, 1.8-23; P-2/P-4 ratio 0.73-0.85. Legs: dL of I-L: 75, 98, 114, 153, 155, 178, I-L-6 H 63, dL/H I-L-6 ratio 2.85. dL of IV-L-1-6: 163, 122, 172, 231, 231, 216. Male — Unknown.