Atractides scutifer ( Lundblad, 1951 )

Pešić, Vladimir, Smit, Harry & Gerecke, Reinhard, 2011, New records of water mites of the genus Atractides Koch, 1837 (Acari: Hydrachnidia, Hygrobatidae) from South Africa, with descriptions of five new species, Zootaxa 2986, pp. 1-54 : 40-46

Atractides scutifer ( Lundblad, 1951)

( Figs. 35–39 )

Megapus scutifer Lundblad 1951: 160 .

Material examined. South Africa, Western Cape province: SA 4 0/2/0 (0/1/0 mounted); DC 108 84 1/1 /0. Mpumalanga province: DC 76 84 6/1 /0; DC 78 84 1/1 /0; DC 85 84 5/2 /0 (1/0/0 mounted). KwaZulu-Natal province: DC 88 84 1/0/0; DC 89 84 2/2 /0; DC 90 84 6/0/0; DC 91 84 1/5 /0. Eastern Cape province: DC 103 84 4/2 /0.

General features. Dorsal integument striated; muscle attachments showing sexual dimorphism; genital field: Ac in obtuse triangular arrangement. Palp: P-4 sword seta large, between ventral hairs, nearer to distoventral hair, P-5 without cheeks. I-L little modified, S-1/2 closely together, bluntly pointed, S-2 basally slightly enlarged; claws with ventral and dorsal clawlets.

Morphology. Male (DC 85 84). Extension of muscle attachment sclerotization variable, from separate platelets (arranged as in Fig. 35A ; postoc on a subtriangular plate covering large part of the dorsum, Dgl-3 fused with D2, Dgl-4 fused with D3, Dgl-5 fused with D4, Dgl-6 fused with D5, all plates rather large and separated, adjacent to each other) to a large dorsal shield with irregular undulating margin including prefr, postoc and Dgl-3–6 ( Fig. 35B ), L/W 375/281; extended ventral shield including coxae, genital field, excretory pore, all ventralia and Vgl, L/ W 413/394, Cx-III W 289. Genital field ( Fig. 36A ): W between outer margins of the most lateral pair of Ac 109, L Ac 1–3: 20, 22, 23; ejaculatory complex ( Fig. 36B ) L 82.

Palp: total L 217, dL: P-1, 28; P-2, 46; P-3, 45; P-4, 72; P-5, 26; L ratio P-2/P-4, 0.64; capitulum vL 145; chelicera total L 167, claw L 54, L basal segment/claw ratio 2.52.

I-L: I-L-5 dL 100, HB 30, dL/HB 3.32, S-1 L 44, L/ W 11.9, S-2 L 47, L/ W 9.2, distance S-1-2, 4.0, L ratio S- 1/2, 0.94; I-L-6 L 71, HB 19, L/HB ratio 3.84; L ratio I-L-5/6, 1.4.

Female (SA 4, in parentheses DC 85 84 [n = 2]; in square brackets DC 103 84 [n = 2]). Idiosoma L/W 759 (431–466) [544–547]/481 (331–356) [389–402]; muscle attachments: postoc on large separate platelets, L/W 128 (183–188) [144–172]/94 (103–106) [102–119]; coxal field with extended border of secondary sclerotization, L 350; Cx-III W 437; Cx-I+II mL 120, lL 263. Genital field ( Fig. 37B ): pregen very robust, with extended border of secondary sclerotization, L/W 175/184; genital plate L 95 [85–90]; pregen W 167; L Ac 1–3: 26, 29, 31; egg maximum diameter (n = 2): 109–120; excretory pore: sclerotized; Vgl-1 fused to Vgl-2.

Palp ( Fig. 39B ): total L 320, dL: P-1, 43; P-2, 66; P-3, 72; P-4, 104; P-5, 35; L ratio P-2/P-4, 0.63; capitulum vL 216 (213–225) [230–250]; chelicera total L 309, claw L 97.

I-L ( Fig. 39A ): I-L-5 dL 143, vL 112, dL/vL ratio 1.28, HB 38.5, dL/HB, S-1 L 69.5, L/ W 12.6, S-2 L 66, L/ W 8.2, distance S-1-2, 7.0, L ratio S-1/2, 1.05; I-L-6 L 102, HB 20, L/HB ratio 5.1; L ratio I-L-5/6, 1.4.

Remarks. The specimens examined fit the descriptions given by Lundblad (1951, 1952) for Atractides scutifer from East Africa, and later reported by K.O. Viets (1963) from South Africa; measurements lie within the range of A. scutifer given by K.O. Viets (1963) for populations from KwaZulu-Natal (Ingwavuma River) and the Mpumalanga (Crocodile River) provinces.

A study of populations from different parts of South Africa shows considerable variation in the extensions of dorsal sclerotization in both sexes. In males, this varies from separate platelets to a large dorsal shield. Due to the similar arrangement of the separate dorsal platelets, males of A. scutifer resemble members of the A. testudo species group ( A. testudo Cook, 1966 , A. pseudotestudo Cook, 1966 , A. neotestudo Cook, 1966 , A. paratestudo Cook, 1966 and A. subtestudo Cook, 1966 ), all known from Liberia ( Cook 1966). Atractides scutifer is most similar to A. testudo due to the arrangement of dorsal platelets and a ventral shield including excretory pore and all Vgl, but differs in the most anterior pair of glandularia being fused medially in the latter species (see: Cook 1966).

In females, variation is found in the dimensions of the dorsal platelets bearing postocularia. Specimens from the Western Cape province (Dwars and Olifants Rivers) differ in minor dimensions of dorsal platelets, L/W 110– 128/80–94 vs. 178/ 128 in holotype (data taken from Lundblad 1952), 157–198/ 106–132 in specimens from the Mpumalanga province (combined data, taken from K.O.Viets 1963 and this study), and 144–172/ 102–119 in specimens from the Eastern Cape. In view of the good agreement in other features, these differences are most probably age-dependt and/or due to geographical variability.

Distribution. South Africa: Mpumalanga province: K.O. Viets (1963), present study; KwaZulu-Natal province: K.O. Viets (1963), present study; Western Cape and Eastern Cape provinces: present study.

Atractides neoscutifer sp. nov. ( Figs. 40–44 )

Type series. Holotype, female, dissected and slide mounted, South Africa, Western Cape province, DC 106 84, unnamed stream on Rt. 60, NW of Swellendam, 20m wide, rocks, stained (10ºC), 15.vi.1984, Cook ( BMSA). Paratypes: 4/1/0 (1/0/0 mounted), same data as holotype ( SMF); SA 17 0/1/0 (mounted) ( RMNH).

General features. Dorsal integument striated; muscle attachments showing sexual dimorphism; genital field: Ac in a little curved line. Palp: P-4 sword seta large, distally from distoventral hair, P-5 without cheeks. I-L little modified, S-1 and -2 closely together, S-2 distally truncate or blunt; claws with ventral and dorsal clawlets.

Description. Female (holotype, in parentheses SA 17). Idiosoma L/W 650 (869)/512 (656); muscle attachments: postoc on small irregularly roundish separate platelet ( Fig. 40 ), L/W 56–63/47–50; coxal field with borders of secondary sclerotization, L 355 (338); medioposterior margin of Cx-I+II strongly curved or truncated, Cx-III W 445 (442); Cx-I+II mL 113, lL 256 (236). Genital field ( Fig. 41 ): L/W 144 (188)/159 (194); pregen very robust, with extended border of secondary sclerotization, W 120 (130); genital plate L 88–89 (98–100); L Ac 1–3: 28 (38– 39), 30 (38–41), 28 (34–39); excretory pore sclerotized; egg maximum diameter (172): Vgl-1 not fused to Vgl-2.

Palp ( Fig. 42B ): total L 353 (334), dL: P-1, 46 (43); P-2, 74 (72); P-3, 81 (74); P-4, 111 (107); P-5, 41 (38); L ratio P-2/P-4, 0.67 (0.67); capitulum vL 229; chelicera ( Fig. 42E ) total L 350 (313), claw L 113 (100), L basal segment/claw ratio 2.31 (2.47).

I-L ( Fig. 42D ): I-L-5 dL 167 (160), vL 132, dL/vL ratio 1.27, HB 38 (36), dL/HB 4.4 (4.4), S-1 L 69 (67), L/ W 9.9 (8.8), S-2 L 67 (64), L/ W 7.3 (9.3), distance S-1–2, 6.0 (6.0), L ratio S-1/2, 1.03 (1.05); I-L-6 L 103 (93), HB 19 (21.5), L/HB ratio 5.5 (4.3); L ratio I-L-5/6, 1.62 (1.7).

Male (DC 106 84): A large dorsal shield with irregular undulating margin including prefr, postoc and Dgl-3-6, L/W 381/311 (Dgl-6 asymetrically fused with, or separate from dorsal shield, Fig. 43B ); extended ventral shield ( Fig. 43A ) including coxae, genital field, excretory pore, all ventralia and Vgl, L 425, Cx-III W 309. Genital field: W between outer margins of the most lateral pair of Ac 99, L Ac 1–3: 17, 16, 17.

Palp ( Fig. 42A ): total L 229, dL: P-1, 29; P-2, 46; P-3, 46; P-4, 80; P-5, 28; L ratio P-2/P-4, 0.58; capitulum vL 138; chelicera total L 177, claw L 62, L basal segment/claw ratio 2.86.

I-L ( Fig. 42C ): I-L-5 dL 112, vL 88, dL/vL ratio 1.27, HB 30, dL/HB 3.7, S-1 L 50, L/ W 9.8, S-2 L 52, L/ W 7.8, distance S-1-2, 4.0, L ratio S-1/2, 0.97; I-L-6 L 73, HB 18, L/HB ratio 4.1; L ratio I-L-5/6, 1.53.

Remarks. Atractides neoscutifer resembles A. scutifer , but postoc on small dorsal platelets on each side (on large extended platelets in A. scutifer ) and unfused Vgl-1 and -2 (fused in A. scutifer ) distinguish female of A. neoscutifer from A. scutifer . Males of A. neoscutifer differ from A. scutifer in having the genital field proportionally longer and narrower (compare Figs. 43A with 36A).

Distribution. South Africa: Western Cape and KwaZulu-Natal provinces.

Figures

FIGURE 40. Atractides neoscutifer sp. nov., female, holotype: idiosoma, dorsal view. Scale bar = 100 μm.

FIGURE 41. Atractides neoscutifer sp. nov., female, holotype: idiosoma, ventral view. Scale bar = 100 μm.

FIGURE 42 A – E. Atractides neoscutifer sp. nov., (A, C = male, paratype; B, D – E = female, holotype): A = palp, lateral view; B = palp, medial view; C – D = I-L- 5 and – 6; E = chelicera. Scale bars = 100 μm.

FIGURE 43 A – B. Atractides neoscutifer sp. nov., male, paratype: A = idiosoma, dventral view; B = idiosoma, dorsal view. Scale bar = 100 μm.

FIGURE 44 A – F. Atractides neoscutifer sp. nov., female, Poacher’s stream: A = idiosoma, dorsal view; B = idiosoma, ventral view; C = palp, medial view; D = I-L- 5 and - 6; E = claw; F = chelicera. Scale bars = 100 μm.

FIGURE 35 A – B. Atractides scutifer (Lundblad, 1951), male, Houtbosloop: A – B = idiosoma, dorsal view. Scale bar = 100 μm.

FIGURE 36 A – B. Atractides scutifer (Lundblad, 1951), male, Houtbosloop: A = idiosoma, ventral view; B = ejaculatory complex. Scale bars = 100 μm.

FIGURE 37 A – B. Atractides scutifer (Lundblad, 1951), female (A = from Houtbosloop; B = from Mooi River): A = idiosoma, dorsal view; B = genital field. Scale bar = 100 μm.

FIGURE 38. Atractides scutifer (Lundblad, 1951), female, Dwars River: A = idiosoma, ventral view. Scale bar = 100 μm.

FIGURE 39 A – B. Atractides scutifer (Lundblad, 1951), female, Dwars River: A = I-L- 5 and - 6; B = palp, medial view. Scale bar = 100 μm.