Hygrobates (Hygrobates) neotrigonicus, Pešić & Esen, 2022

Pešić, Vladimir & Esen, Yunus, 2022, Integrative description of a new species of water mite genus Hygrobates (Acariformes, Hydrachnidia, Hygrobatidae) from Türkiye, Ecologica Montenegrina 57, pp. 98-108 : 102-104

Hygrobates (Hygrobates) neotrigonicus sp. nov.

https://zoobank.org/ urn:lsid:zoobank.org:act:5171CE9B-B4C0-4CF8-93FF-CFFDB191A5AD

Figs 3-4

Material examined — Holotype ♂ ( RMNH), sequenced [ BOLD Process ID: DCDDJ053-21 ; voucher code: CCDB 38361 E05], dissected and slide mounted, Türkiye, Bingöl Province, Cevrimpinar stream, 38.9092 N, 40.4744 E, 1097 m asl., 29 May 2021, leg. Esen. Paratypes: 1♀ [sequenced; BOLD Process ID: HYDME051-22 ; voucher code: CCDB 41823 E03], same site as holotype, 15 May 2021, leg. Esen, dissected and slide mounted ( RMNH) ; 1♂, Capakcur stream [sequenced; BOLD Process ID: HYDME052-22 ; voucher code: CCDB 41823 E04], 38.8936 N, 40.4772 E, 1147 m asl., 28 May 2021 leg. Esen ( RMNH) .

Compared material — Hygrobates trigonicus : 1♂, 1♀, Germany, Peene , Dr Krüger coll. ex coll K. Viets; 1♂, 1♀, Greece, GR48 Makedonia ( SER), Vrondus , Sidirokastron, Krusovitis Potamos, 180 m, QK 32 09, 02.06.1991, leg. Bückle & Gerecke, det. Gerecke.

Diagnosis — Posterior margin of male genital field indented with a large medial projection; Ac-3 subtriangular; female pregenital sclerite with four setae.

Description. General Features — Colour yellow to brown. Integument finely striated. Posteromedial margin of Cx-I rounded, caudo-lateral apodemes of Cx-I+II slightly developed ( Fig. 3A ); Cx-IV subtriangular in shape, with anterior and posterior margins converging to median line. Anterior margin of genital field convex, with a small medial projection, typically with irregular margin of a secondary sclerotization, posterior margin due to the secondary sclerotization without indentation, with a small centrally rounded projection, Ac in obtuse line ( Figs. 3 B-C). Gnathosoma anteriorly with clearly offset projections. P-2 ventral margin straight, distally forming a slightly knob-shaped projection covered by large, scattered denticles, P-3 with large, scattered denticles covering distal two thirds of ventral margin; P-4 ventral setae separated, ( Figs. 3 D-E). IV-L-5 with one distal swimming seta. Male — Anterior margin of genital field convexly rounded, posterior margin indented with a large medial projection, Ac-3 subtriangular ( Figs. 3 A-B). Female — Genital plates sickle-shaped, with strongly concave medial margins, pregenital sclerite with four setae, pregenital and postgenital sclerite with a extended border of a porose secondary sclerotization ( Fig. 3C ); P-4 more slender than in male.

Measurements. Male (holotype CCDB 38361 E05; in parentheses some measurements of paratype CCDB 41823 E04) — Idiosoma L 830 (806), W 690 (706); coxal field: L 328; Cx-III W 416; mL of Cx-I + gnathosoma L 288; distance between lateralmost ends of caudo-lateral Cx-II apodemes, 134; genital field L/W 156 (172)/145 (145), ratio; L Ac 1-3: 49-52 (50-53), 39-63 (55-63), 52-55 (50-58). Ejaculatory complex L 164.

Chelicera total L 281, L basal segment 188, claw 99, L basal segment/claw ratio 1.9. Palp: total L 360; dL/H, dL/H ratio: P-1, 28/33, 0.86; P-2, 94/64, 1.46; P-3, 69/54, 1.27; P-4, 117/38, 3.1 (basal H 27, dL/basal H ratio 4.4); P-5, 52/19, 2.8; P-2/P-4 ratio 0.8.

Legs: dL of I-L-1-6: 56, 69, 81, 122, 125, 130. dL of IV-L-1-6: 119, 97, 146, 203, 219, 197.

Female — Idiosoma L 863, W 744; coxal field: L 338; Cx-III W 425; mL of Cx-I + gnathosoma L 286; distance between lateralmost ends of caudo-lateral Cx-II apodemes, 128; genital field L/W 219/203; genital plates L 163-165; pregenital sclerite W 58; gonopore L 153; L Ac 1-3: 56-61, 52-58, 42-44. Egg maximum diameter (n = 2) 156-158.

Chelicera total L 269, L basal segment 180, claw 103, L basal segment/claw ratio 1.75. Palp: total L 396; dL/H, dL/H ratio: P-1, 28/36, 0.79; P-2, 106/63, 1.7; P-3, 77/55, 1.4; P-4, 130/38, 3.5 (basal H 31, dL/basal H ratio 4.2); P-5, 55/18, 3.0; P-2/P-4 ratio 0.82.

Legs: dL of I-L-1-6: 59, 73, 94, 131, 134, 138. dL of IV-L-1-6: 117, 103, 150, 219, 227, 211.

Etymology — Named after its similarity with H. trigonicus . Remarks — The phylogenetic analysis based on COI data placed the specimens from Eastern Türkiye here described as a new species, i.e. Hygrobates neotrigonicus sp. nov., as a sister of a clade which comprises two European clades of H. trigonicus . The results of our study reveals a high interspecific distance between the Turkish clade and its European sister clades. The level of COI differentiation between the Turkish clade and the H. trigonicus clades from Germany and Greece was estimated to be 19.0±2.0% and 16.6 ±1.7% K2P, respectively, thus confirming the validity of the species from Türkiye, proved also by the results of the ASAP Analysis.

According to Pešić et al. (2021) the taxonomic status of European H. trigonicus clades from Germany and Greece should be clarified by resolving the taxonomic status of H. properus Láska, 1954 . The recent study of Pešić et al. (2021) revealed that genetic distance between two European H. trigonicus clades are of interspecific level. For now it seems most appropriate to leave unnamed the Greece-clade until the material from the type locality of both taxa becomes available. On the other hand, it is unlikely that the clade that comprises of individuals from Eastern Türkiye belong to H. properus . Therefore, we describe it here as a new species, i.e. H. neotrigonicus sp. nov. (see below).

Morphologically, the populations from Germany which likely should be assigned to nominal H. trigonicus can be separated by a less triangular (and more roundish) Ac- 3 in both sexes. In specimens from Greece, the third acetabulum is more elongated, similar to condition found in specimens of the new species from Türkiye, from which it can be distinguished by the posterior margin of the male genital field which is convex due to the secondary sclerotization and without indentation. These small morphological differences obviously do not reflect a significant genetic distances between the examined populations.

Distribution — Türkiye; so far only known from two streams ( Figs. 6 A-B) in Eastern Türkiye (Bingöl Province).

Figures

Figure 3. Hygrobates neotrigonicus sp. nov. (A, D – ♂ holotype; B – ♂ paratype; C, E-F –♀ paratype). A – coxal and genital field; B-C – genital field; D – palp, medial view; E – palp, lateral view; F – chelicera. Scale bars = 100 μm.

Figure 4. Hygrobates neotrigonicus sp. nov., ♂. A – I-leg; B – IV-leg. Scale bar = 100 μm

Figure 6. Sample site of Hygrobates neotrigonicus sp. nov. in Eastern Türkiye (Bingöl Province): A – Cevrimpinar stream. B – Capakcur stream. Photos by Yunus Esen.