Atractides (s. str.) asinus, Gerecke, 2021

Gerecke, Reinhard, 2021, The water mites of the family Hygrobatidae (Acari, Hydrachnidia) in Italy, Zootaxa 5009 (1), pp. 1-85 : 9-12

Atractides (s. str.) asinus sp. nov.

(Figs 3-4; 27 G)

Type series: Holotype ♂, SMF, Sicilia: I 56 Etna ( ME), Giardini Naxos, Fiume Alcantara , 20 m, UTM WB 21 85, 10.06.1985 Gerecke . Paratypes: same site and date, 1/25/0 slide ( SMF); 1/1/0 slide ( NHMW) .

Further material: Calabria: Pellegrino mountains, I 1065, 0/4/0 (0/1/0 slide); Sicilia: Peloritani, Etna; I 134, 0/7/0 slide; I dp 83, 0/1/0 slide.

Diagnosis: Dorsal integument very finely striated; muscle insertions and excretory pore, smooth, glandularia small; Vgl-1/2 separate. Genital field with small Ac in a weakly curved line. I-L-5 enlarged near insertion of S-1, S-1-2 close to each other, straight and blunt, S-1 apically with a very fine adaxial tip. I-L-6 curved (Figs 3 B, 4 B). Palp with weak sexual dimorphism, Males: Genital field anterior margin convex, posterior margin in central part concave (Fig. 3 C-D). P-2 ventral distally slightly protruding, P-4 rather stout and with dense dorsal setation (Fig. 3 A). Females: Genital plates anteriorly rounded (Fig. 4 A), P-2 ventral margin weakly convex, P-4 slenderer than in males and with more scattered setation (Fig. 4 C).

Fig. 3: Atractides asinus sp. nov., type series ♂ (I 56). A, palp; B, I-L-5/6; C, venter; D, genital field with setation. Scale bars: 100 µm.

Description: Lateral eyes well developed and pigmented; glandularia maximum diameter 15-18. Coxal plates in three groups. Posterior margin of Cx-I+II narrow, rounded, posterior apodemes of Cx-I forming an obtuse angle. I-L-5 stout, dorsal and ventral margins in distal half distinctly diverging, ventral seta in distal third (distance to distal edge 33-45 % vL); S-1 maximum W near base, here with a fine adaxial kink, apically slightly enlarged to form a very fine adaxial tip; S-2 slightly stouter, maximum width in basal third. I-L-6 stout and curved, proximally slightly thicker than in the centre and apically. Genital field with Ac-3 distinctly larger than Ac-1/2. Gnathosoma with short rostrum, chelicera normal in proportions (L/H 4.7-5.6, basal segment/claw ratio 2.3-2.6). P-4 maximum H on the level of proximoventral seta, sword seta near proximoventral seta; seta insertions dividing margin into three subequal sectors (relative length in %: 32-41/32-40/24-36).

Males (n = 2): Idiosoma L/W 450-460/330-350; coxal field L/Cx-III W 250-270/280-290, Cx-I+II mL 95-100, lL 170, W 230-250 (mL/W ratio 0.38-0,43). Genital field broadly rounded (L/W 72-80/72, ratio 1.0-1.1) with about 18 pairs of setae; Ac-1-3 maximum diameter 18-20, 18-20, 20-24, gonopore L 40-45; anterior margin convex, posterior margin with a weakly concave medial indentation. I-L-5 dL/vL 132-136/96-106, ratio 1.28-1.38; HA 33- 35, HB 43-44, HC 48, ratio dL/HB 3.0-3.2; L (L/W) S-1, 68 (10.8-13.5), S-2, 60-63 (8.0-8.3), distance S-1-2, 9-10, ratio S-1 L/distance S-1-2, 6.8-7.7. I-L-6 L 100-104, HA 25-26, HB 20-21, HC 19-20, ratio L/HB 4.7-5.2; ratio I- L-5 dL/I-L-6 L 1.3. Palp total L 229-231; proportions of segments (L/H, ratio, % total L): P-1, 25/23, 1.1, 11; P-2, 50/44-45, 1.11-1.14, 22; P-3, 50-53/35, 1.4-1.5, 22-23; P-4, 75-76/28, 2.7-2.8, 32-33; P-5, 28-29/10-11, 2.6-2.8, 12; L ratio P-2/P-3, 0.95-1.00, P-2/P-4, 0.66-0.67; P-3/P-4, 0.66-0.70. P-2 ventral margin in distal part forming a blunt protrusion; P-3 ventral margin nearly straight, P-4 sword seta in the centre (ratio distance to proximal/distal edge 0.9-1.3).

Fig. 4: Atractides asinus sp. nov., paratype ♀ (I 56). A, genital field; B, I-L-5/6; C, palp. Scale bar: 100 µm.

Females (n = 4): Idiosoma L/W 550-720/400-480; coxal field L/Cx-III W 280-310/330-370, Cx-I+II mL 110- 125, lL 180-210, W 260-280 (mL/W ratio 0.42-0,46). Genital field L 110-140, with elongate acetabular plates (L/W 84-90/26-28, ratio 3.0-3.3); Ac-1-3 maximum diameter 22-24, 22-24, 22-26, pregenital sclerite crescent-shaped. I-L-5 dL/vL 152-164/116-128, ratio 1.28-1.34; HA 38-45, HB 45-53, HC 53-55, ratio dL/HB 3.1-3.4. L (L/W) S-1, 75-78 (10.0-12.4), S-2, 68-73 (6.8-9.3), distance S-1-2, 10-11, ratio S-1 L/distance S-1-2, 6.9-7.8. I-L-6 L 108-116, HA 25-30, HB 23-24, HC 21-23, ratio L/HB 4.8-5.2; ratio I-L-5 dL/I-L-6 L 1.4. Palp slenderer than in males, total L 260-280; proportions of segments (L/H, ratio, % total L): P-1, 25-30/24-26, 1.1-1.2, 9-11; P-2, 55-60/43-45, 1.3-1.4, 21-22; P-3, 65-73/31-38, 1.9-2.1, 25-26; P-4, 83-88/24-25, 3.0-3.6, 31-32; P-5, 30-33/11-13, 2.4-2.7, 11-12; L ratio P-2/P-3, 0.83-0.87, P-2/P-4, 0.66-0.69; P-3/P-4, 0.76-0.83. P-2 ventral margin straight, with a rounded distal edge; P-3 ventral margin straight, P-4 sword seta in distal half (ratio distance to proximal/distal edge 1.1-1.3).

Derivatio nominis: Honouring the donkey ( Equus asinus ).

Discussion: In the combination of a finely striated integument with unsclerotized muscle insertions, smooth excretory pore, unfused Vgl-1/2, shape of palp, and in general dimensions, A. asinus resembles most A. neumani Lundblad, 1962a , a little-known species recorded from Sweden and Poland. Both sexes of A. neumani differ from A. asinus in Ac in a more triangular arrangement and major in size (maximum diameter> 30), and in slightly slenderer segments I-L-5 (dL/HB ratio> 3.4) and I-L-6 (dL/HB ratio> 6.0). Furthermore, male A. neumani differ in a longer medial suture Cx-I+II (> 120) and genital field (> 100). Among other species not treated here, female A. asinus resemble A. angelieri Pešić, Smit, & Gerecke, 2012 from S France, a species in the male sex clearly distinguished by a prominent ventral projection of P-2. Both sexes of A. angelieri differ from A. asinus in Ac major in size (maximum diameter> 30), females also in a longer acetabular plate (99-115), a higher L ratio P-2/P-4 (> 0.70), and a stouter I-L-5 (dL/HB 2.9).

Habitat: Rhithrobiont. All records from sun-exposed streams at low to middle altitudes, 20- 355 m.

Distribution: Calabria, Sicily.

Fig. 5: Atractides asticae ♀ (I 510 Int). A, gnathosoma with chelicera and palp, lateral; B, I-L-4-6. Scale bar: 100 µm.