Atractides valencianus K. Viets, 1930

Gerecke, Reinhard, 2014, The water mites of the genus Atractides Koch, 1837 (Acari, Hydrachnidia: Hygrobatidae) in Corsica and Sardinia, Zoosystema 36 (4), pp. 735-759 : 755-757

Atractides valencianus K. Viets, 1930

MATERIAL EXAMINED. — Sardinia.: I 350, 1 ♀, 3 dn ; I 359, 1 ♀; I 370b, 1 ♀; I 381, 1 ♀; I 389, 1 ♀; I 1159, 2 ♀♀ (MNHN) .

Sardinia. I 350, 1 ♀ ; I 387, 1 ♂; I 389, 2 ♀♀; I 1159, 2 ♀♀ (Coll. RG) .

UNCERTAIN RECORDS ( SEE BELOW). — Sardinia. I 380, 1 ♀ ; I 388, 1 ♀.

DISTRIBUTION. — West Mediterranean. First record from the area covered; new for Italy.

HABITAT. — Rhithrobiont. Medium order streams, in the area coeverd from 20 to 1400 m.

REMARKS

As in the case of A. inflatipalpis , a species similar from many points of view (see above), also the variability of A. valencianus is still little documented. In the following, measurement ranges and some morphological details are given for the specimens from the area covered, and the differences between the two species are discussed.

Both sexes

Glandularia small, round, also dorsocentrally with relatively short setae. Coxae without secondary sclerotization. I-L-5 elongated, ventral margin distal to ventral seta concave, forming a blunt projection near S-1 insertion in the area between S-1 and -2 parallel to dorsal margin; S-1 long and slender, distally equally narrowed, tip oblique truncated, forming a fine denticle on the inner side; S-2 distinctly shorter, slightly enlarged in proximal third, tip bluntly pointed. Palp with weak sexual dimorphism; P-4 with maximum H near proximoventral seta, sword seta near distoventral seta insertions, proximal and distal ventral sectors slightly shorter than central one.

Male (n = 1)

Idiosoma L/W 600/420, coxal field L/W 350/390; Cx-I+II medial L 100, lateral L 245, W 300. I-L-5 dL/vL 200/1/45, ratio 1.4; HA 48, HB 55, HC 68, ratio dL/HB 3.6; S-1 L/W 93/7, ratio 13.2; S-2 L/W 80/8, ratio 10.0; distance S-1-2, 18, L ratio S-1/-2, 1.2; I-L-6 dL 145, HA 28, HB 25, HC 26; ratio dL/HB 5.8; dL ratio I-L-5/6, 1.38. Genital field L/W 110/125, rounded, anterior margin slightly convex, posterior margin with a shallow medial indentation; gonopore L 65, acetabula in a curved line, surrounded by 28-36 pairs of setae (fine, hair like laterally, longer and stronger, in a double or triple line medially, single longer setae at antero- and posterolateral edges of acetabula). Palp total L 343; L/H (ratio, rel. L [%]) P-1, 33/35 (0.9, 9); P-2, 80/65 (1.2, 23); P-3, 80/50 (1.6, 23); P-4, 113/45 (2.5, 33); P-5, 38/11 (3.3, 11); L ratio P-2/P-4, 0.71; P-3/P-4, 0.71. P-2 ventral margin proximally concave, distally convexly protruding, forming an acute angle with distal margin; P-3 relatively short and stout, ventral and dorsal margins diverging, distal quarter of ventral margin hyaline P-4 with dense cover of fine, hair-like setae.

Females (n = 7)

Idiosoma L/W 650-850/460-650, coxal field L/W 340-380/400-510; Cx-I+II medial L 90-125, lateral L 215-250, W 305-350. I-L-5 dL/vL 210- 225/140-149, ratio 1.5-1.6; HA 53-60, HB 58-69, HC 80-90, ratio dL/HB 3.1-3.9; S-1 L/W 113- 120/9-10, ratio 11.3-12.9; S-2 L/W 90-100/13-15, ratio 6.3-7.5; distance S-1-2, 28-35, L ratio S-1/-2, 1.2-1.3; I-L-6 dL 163-170, HA 28-31, HB 18-20, HC 21-25; ratio dL/HB 8.1-9.4; dL ratio I-L-5/6, 1.27-1.35. Genital field L/W 130-170/160-190, pre- and postgenital sclerites strong, genital plates L/W 110-115/30-35, weakly curved, anteriorly and posteriorly rounded, bearing 10-12 pairs of fine, hair-like setae; Ac-3 often distinctly larger than Ac-2. Palp total L 335-370; L/H (ratio, rel. L [%]) P-1, 35- 38/29-33 (1.1-1.3, 10-11);P-2, 73-80/53-60 (1.3-1.4, 22-23); P-3, 83-100/39-55 (2.0-2.5, 24-27); P-4, 110-118/28-31 (3.5-4.0, 32-33); P-5, 33-40/11-14 (2.6-3.1, 10-11); L ratio P-2/P-4, 0.65-0.70; P-3/P-4, 0.74-0.85. P-2 ventral margin concave in proximal, convex in distal half, with slightly rugose surface; P-3 and -4 long and more slender than in males, ventral margin P- 3 in distal half hyaline.

Excluded from this measurement series are two females (I 380, I 388) which agree in most morphological details, but have distinctly larger measurements - e.g., idiosoma L/W 900-1300/650-900; genital plate L 123-145; palp total L 440-475, P-3 L/H 113-128/55-65, I-L-5 dL/vL 255-280/180- 195. These specimens differ also in proportions of segments (most significant: relative L P-2 major, 24 %, P-4 minor, 30 %, P-2/4 L ratio 0.81-0.83; P-4 stouter, L/H 3.2-3.4; I-L-5 dL/vL ratio minor, 1.42-1.44, and segment more slender, L/HB 3.8- 3.9. Studies of further populations are necessary in order to make clear if these data indicate a wider variability range of A. valencianus , or the presence of a further species from the taxonomic neighbourhood A. inflatipalpis / A. valencianus in the area covered.

REMARKS

Both sexes of A. inflatipalpis differ from A. valencianus mostly in the shape of I-L-5/6, with: (1) a higher dL/ vL ratio of I-L-5 (males:> 1.5, females> 1.6), (2) a stouter S-2 with more strongly inflated inner margin (L/W in males <7.0, in females <6.0), (3) a higher distance S-1-2 (> 25 in males,> 35 in females), and (4) a lower I-L-5/6 dL ratio (<1.30 in males, <1.25 in females). In the male sex, A. inflatipalpis differs from A. valencianus furthermore in a more slender P-4 (L/H> 2.65) with the sword seta located more distally, but in first line in the by far weaker setation of the genital field. This latter character state is well visible in published figures (e.g., Gerecke 2003), but has not been taken in consideration so far: on each side of the anterior gonopore, in A. inflatipalpis , 7-8 setae are inserted in a single line flanking the medial margin of Ac-1. Instead, in A. valencianus this area is covered by 12-20 paired setae arranged in double or triple lines and posteriorly extending until the anterior margin of Ac-3.