Hygrobates (Hygrobates) tyrrhenicus Pešić & Smit, 2022

Pešić, Vladimir, Esen, Yunus, Gerecke, Reinhard, Goldschmidt, Tom, Mumladze, Levan, Smit, Harry & Zawal, Andrzej, 2022, Evidence of cryptic speciation in the Hygrobates calliger complex (Acariformes, Hydrachnidia, Hygrobatidae) with the description of two new species, Ecologica Montenegrina 59, pp. 101-122 : 114-115

Hygrobates (Hygrobates) tyrrhenicus Pešić & Smit sp. nov.

https://zoobank.org/ urn:lsid:zoobank.org:act:CD2E889A-FF8C-478C-8D52-A8DBBA6413F4

Figures 8-9

Type examined — Holotype ♂ ( RMNH), dissected and slide mounted [sequenced; BOLD /GenBank: NOVMB056-21 /ON002563; voucher code: CCDB 38559 A08], France, Corsica, Rivière La Solenzara , 41.8383 N, 9.33055 E, 7 April 2021, leg. Smit. Paratypes: 1♀ [sequenced; BOLD /GenBank: NOVMB007 -

21/ON002565; voucher code: CCDB 38559 A07], France, Corsica, Ruisseau de l‘Umbert acciu, at Pont Chiuni /D81, 42.1838 N, 8.61712 E, 13 April 2015, leg. Smit, dissected and slide mounted ( RMNH) .

Diagnosis — Dorsal lines interspace 11-12; P-2 with triangular, bluntly pointed, comparatively long (L/W ratio 1.3) ventrodistal projection. Anterior margin of male genital field with a very shallow indentation and a small knob-shaped medial projection in the centre of indentation, male genital field L/W ratio 0.78; female gonopore longer than genital plates.

Description. General Features — Colour yellow to brown. Integument soft, strongly lineated. Posteromedial margin of Cx-I+II obtuse-triangular, caudo-lateral apodemes of Cx-I+II moderately developed; Cx-IV subtriangular, with a distinct nose-like protruding medial margin. Ac-2 and Ac-3 placed next to each other, arranged in a triangle. P-2 ventral margin proximally concave, distally forming a triangular, bluntly pointed projection covered by small, scattered denticles, P-3 with denticles covering distal two thirds of ventral margin; P-4 ventral setae separated ( Figures 8 A-B). Male — Genital field typically with irregular margin of secondary sclerotization, anterior margin with a very shallow indentation and a small knob-shaped medial projection, posterior margin deeply indented with a rounded protrusion in the centre of indentation, not extending beyond posterior margin ( Figure 8A ). Female — Genital plates with a narrow border of a porose secondary sclerotization ( Figure 9A ); P-4 more slender than in male.

Measurements. Male (holotype) — Idiosoma L 994, W 788; coxal field: L 450; Cx-III W 519; mL of Cx-I + gnathosoma 372; distance between lateralmost ends of caudo-lateral Cx-II apodemes 168; genital field L/W 154/197, ratio 0.78; L Ac 1-3: 53-56, 72-74, 63. Ejaculatory complex L 200.

Chelicera total L 317, L basal segment 216, claw 125, L basal segment/claw ratio 1.7. Palp: total L 554; dL/H, dL/H ratio: P-1, 38/46, 0.81; P-2, 138/92 1.5; P-3, 119/84, 1.4; P-4, 195/44 4.45; P-5, 64/23, 2.7; P-2/P-4 ratio 0.71; L/W P-2 ventrodistal projection ratio 1.3; P-4 ventral setae distance 35.

Legs: dL of I-L-2-6: 106, 143, 222, 225, 194; L of longest I-L-6 distoventral seta 70; L distoventral seta/I-L-6 ratio 0.36; dL of IV-L-1-6: 163, 159, 225, 334, 366, 283.

Female (paratype) — Idiosoma L 1050; coxal field: L 467; Cx-III W 584; mL of Cx-I + gnathosoma 367; distance between lateralmost ends of caudo-lateral Cx-II apodemes 163; genital field L/W 209/230; genital plates L 143-150; pregenital sclerite W 103; gonopore L 173; L Ac 1-3: 49-53, 58-59, 57-59. Egg maximum diameter (n = 2) 150-156.

Chelicera total L 383, L basal segment 256, claw 131, L basal segment/claw ratio 1.95. Palp: total L 580; dL/H, dL/H ratio: P-1, 45/50, 0.9; P-2, 141/98, 1.44; P-3, 125/92, 1.36; P-4, 202/48, 4.2; P-5, 67/24, 2.8; P-2/P-4 ratio 0.7; L/W P-2 ventrodistal projection ratio 1.3; P-4 ventral setae distance 43.

Legs: dL of I-L-1-6: 84, 109, 147, 225, 222, 193; L of longest I-L-6 distoventral seta 70; L distoventral seta/I-L-6 ratio 0.36; dL of IV-L-1-6: 183, 163, 228, 338, 363, 288.

Etymology — The name refers to the Tyrrhenian region where the new species was found.

Discussion — In regard to the presence of a long and slender ventrodistal projection on P-2, specimens of clade 4 from Corsica, here described as H. tyrrhenicus sp. nov. resemble specimens of H. calliger clade 3 which includes specimens from Calabria, Italy ( Figure 1 ). COI barcode-based analysis clearly differentiates these two clades. According to COI sequence analysis, the lineages from Corsica and Calabria are separated by a high genetic distance (20.2±2.1% K2P) indicating a long independent history of these two species.

Morphologically, specimens of clade 3 can be separated from the new species from Corsica by the comparatively more elongated and pointed ventrodistal projection of P-2 and the differently-shaped genital field in both sexes (compare Figures 8A and 9A with Figures 7A, C ). Hygrobates calliger latilaminatus K. Viets, 1930 (in parentheses data from the original description) has a more elongated P-2 ventrodistal projection (L/W ratio 1.86) and a comparatively wider male genital field (L/W ratio 0.64-0.67).

Remarks — Records of H. calliger from Corsica by Pešić & Smit (2022) refer to H. tyrrhenicus sp. nov.

Distribution — Corsica ( France).

Figures

Figure 1. Maximum Likelihood tree of the Hygrobates calliger-complex obtained from 45 nucleotide COI sequences. The results of species delimitation by ASAP procedure are indicated by vertical bars. Outgroup species are given in bold.

Figure 7. Hygrobates calliger clade 3 (A-B, ♂ CCDB 38392 D12, Sila, Italy; C-D, ♀ CCDB 38392 A04, Serra San Bruno, Italy): A – posteromedial margin of Cx-I+II, medial margin of Cx-IV and genital field; B – palp, medial view (inset: P-2 ventrodistal projection, 2x enlarged); C – genital field; D – Palp, lateral view (inset: P-2 ventrodistal projection, 2x enlarged). Scale bar = 100 μm.

Figure 8. Hygrobates tyrrhenicus sp. nov., ♂ holotype CCDB 38559 E08, Riviere La Solenzara, France: A – genital and coxal field; B – palp, medial view (inset: P-2 ventrodistal projection, 2x enlarged); C – palp, lateral view (inset: P-2 ventrodistal projection, 2x enlarged). Scale bar = 100 μm.

Figure 9. Hygrobates tyrrhenicus sp. nov., ♀ paratype CCDB 38559 A07, Ruisseau de l’Umbert acciu, Corsica: A – posteromedial margin of Cx-I+II, medial margin of Cx-IV and genital field; B – palp, medial view (inset: P-2 ventrodistal projection, 2x enlarged); C – chelicera; C – I-L-4-6. Scale bar = 100 μm.