Atractides giustinii Gerecke & Di Sabatino, 2013

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 : 748-750

Atractides giustinii Gerecke & Di Sabatino, 2013

MATERIAL EXAMINED. — Corsica. F 81, 1 ♂. Sardinia. I 335, 1 ♂, 1 ♀ ; I 372, 1 ♀; I 376, 1 ♀; I 381, 1 ♂; I 382, 1 ♂ ( MNHN) .

Sardinia. I 386, 1 ♂, 2 ♀♀ ; I 388, 1 ♀; I 1162, 1 ♂ (Coll. RG) .

PUBLISHED RECORDS. — Corsica. benf 54, 1 ♀ ; benf 59, 2 ♀♀; benf 77, 2 ♂♂, 1 ♀; benf 90, 2 ♂♂, 1 ♀; benf 171,

2 ♂♂, 1 ♀ ( Gerecke & Di Sabatino 2013, MCSNV). DISTRIBUTION. — Corsica, Sardinia, endemic. First record from Sardinia, new for Italy.

HABITAT. — Rhithrobiont. Middle order streams in the macchia vegetation belt, in the area covered from 100 to 800 m.

Atractides gracilipes (E. Angelier, 1951) ( Fig. 2 )

MATERIAL EXAMINED. — Sardinia. I 1162 int, 1 ♂ ; I 1165 int, 1 ♀ (MNHN) .

Corsica. HM 04, 1 ♀ (Coll. HM). PUBLISHED RECORD. — Corsica. Ang 26, 1 ♂ ( Angelier

1954a, holotype, lost).

DISTRIBUTION. — Corsica, Sardinia, endemic. First record from Sardinia, new for Italy.

HABITAT. — Hyporheobiont (judging from the few data available). Middle order streams in the macchia vegetation belt, all specimens found in the interstitial habitat, from 30 to 800 m.

REDESCRIPTION

Both sexes

Integument finely striated, muscle insertions in the female from Corsica partly sclerotized (D-2 as small round platelets, D-3 elongated, medially fused to Dgl-4,V-1 as larger rounded platelets).This is probably the typical situation in adults, with the sclerotization in males to be expected more extended than in females; the specimens from Sardinia are juveniles with unsclerotized muscle attachments, but areas of granulate integument at the places of D-2, D-3 and V-1. Glandularia small, round; coxae in three groups, posteromedial margin Cx-I+II pointed. I-L-5 with ventral and dorsal margins slightly diverging from base to S-1 insertion, ventral seta doubled, ventral margin not particularly protruding near S-1 insertion; S-1-2 not far distanced, long and slender, distally equally narrowed, tip rounded; S-1 slightly bowed inwards in basal part; S-2 shorter, slightly thickened in proximal half. I-L-6 ventral margin convex in proximal and distal part, in the centre, where the segment is distinctly narrowed, strongly concave. Excretory pore surrounded by a sclerotized ring, Vgl-I+II fused. Gnathosoma without particularly projecting rostrum, palp without sexual dimorphism; P-2 ventral margin strongly convex in distal part, without particular extension;P-3ventral margin weakly rounded, P-4 maximum H near proximoventral seta, sword seta between ventral seta insertions, closer to proximoventral one, ventral sectors 2:3:2.

Male

Idiosoma L/W 600/400, venter: Fig. 2A ; coxal field L/W 340/340; Cx-I+II medial L 150, lateral L 235, W 270. I-L-5/6: Fig. 2B ; I-L-5 dL/vL 155/114, ratio 1.3; HA 43, HB 50, HC 58, ratio dL/HB 3.1; S-1 L/W 100/9.5, ratio 10.5; S-2 L/W 80/10, ratio 8.0; distance S-1-2,15, L ratio S-1/-2, 1.3; I-L-6 dL 123, HA 26, HB 18, HC 24; ratio dL/HB 7.0; dL ratio I-L-5/6, 1.27. Genital field L/W 110/120, rounded, antero- and posteromedial margins nearly straight; gonopore shortened (L 50), acetabula subtriangular, surrounded by about 20 pairs of setae (fine, hair like laterally, longer and stronger medially and at posteromedial edge). Palp ( Fig. 2C ) total L 333; L/H (ratio, rel. L [%]) P-1, 30/28 (1.1, 9); P-2, 70/58 (1. 2, 21); P-3, 85/52 (1.7, 26); P-4, 125/35 (3.6, 38) [H and L/H measurements influenced by crushing]; P-5, 23/13 (1.8, 7); L ratio P-2/P-4, 0.56; P-3/P-4, 0.68.

Females (I 1165, in parentheses mature specimen HM 04)

Idiosoma L/W 670/460 (900/750), venter: Fig. 2D ; coxal field L/W 415/460 (390/480); Cx-I+II medial L 160 (160), lateral L 250 (270), W 310 (330). I-L-5/6: Fig. 2F ; I-L-5 dL/vL 215/160 (205/145), ratio 1.3 (1.4); HA 50 (60), HB 58 (65), HC 75 (76), ratio dL/HB 3.7 (3.5); S-1 L/W 135/11 (120/11), ratio 12.0 (11.0); S-2 L/W 103/16 (98/15), ratio 6.3 (6.5); distance S-1-2, 25 (23), L ratio S-1/-2, 1.3 (1.2); I-L-6 dL 168 (155), HA 30 (29), HB 16 (16), HC 23 (23); ratio dL/HB 10.3 (9.7); dL ratio I-L-5/6, 1.28 (1.32). Genital field L/W 130/135 (damaged), pregenital sclerite fine and slender, also in the mature specimen (W 70), postgenital sclerites weakly developed in juvenile specimen, in mature specimen pentagonal, genital plates L/W 100/35 (110/42), weakly curved, anteriorly bluntly pointed, posteriorly rounded, bearing about ten pairs of fine, hair-like setae. Palp of juvenile ( Fig. 2E ): total L 454; L/H (ratio, rel. L [%]) P-1, 34/33 (1.0, 7); P-2, 93/68 (1.4, 20); P-3, 123/60 (2.0, 27); P-4, 163/34 (4.8, 36); P-5, 43/18 (2.4, 9); L ratio P-2/P-4, 0.57; P-3/P-4, 0.75. Palp of mature specimen: total L 444; L/H (ratio, rel. L [%]) P-1, 33/35 (0.9, 7); P-2, 90/75 (1.2, 20); P-3, 120/75 (1.6, 27); P-4, 158/43 (3.7, 35); P-5, 43/16 (4.8, 10); L ratio P-2/P-4, 0.56; P-3/P-4, 0.75.

REMARKS

From investigations on the heritage Angelier results that the male holotype and only existing specimen of A. gracilipes is lost. Consequently, the character combination of this taxon can be deduced only from the information given in the preliminary diagnosis ( Angelier1951)and a more detailed description published by Angelier in 1954a: (1) idiosoma L/W 600/450, integument “fine”(probably striated) with small dorsal and posteroventral glandularia, without sclerotized muscle insertions; (2) coxal field L/W 320/420; with narrow, pointed posteromedial edge of Cx-I,Cx-III+IV medial margin rounded, posterior margin nearly straight; (3) I-L-5 slender, dorsal and ventral margins subparallel, S-1/2 close to each other, heteromorphic (L S-1, 95; S-2, 75, distinctly broader than S-1); (4) I-L-6 equally curved, distally not narrowed, L I-L-5/6, 150/120 (ratio 1.25); (5) genital field nearly circular, with a narrow posteromedial indentation; gonopore relatively short, extending between the levels of anterior margins of Ac-1 and Ac-3, acetabula relatively small, subtriangular; (6) excretory pore with sclerotized ring, Vgl-1+2 fused; (7) palp robust, P-2 ventral margin rounded, without projection, P-4 central ventral sector slightly longer than proximal and distal one, sword seta between ventral setae, more proximal; L/H P-1, 25/25; P-2, 80/55; P-3, 90/47; P-4, 130/38; P-5, 37/-.

In most character states, the male found in interstitial habitat in Sardinia agrees well with the description of A. gracilipes . Of particular significance is the narrow, pointed posteromedial margin of Cx- I+II which is not found in any of the species treated here. Also most measurements of the described male are close to the data published by Angelier, but the following differences in comparison with Angelier’s figures merit discussion: 1) Angelier (1954a) figures S-1/2 with pointed, not rounded tips. As in syntypes of A. corsicus , another species figured with pointed setae S-1/2 by Angelier (1954b), tips of these setae were found truncated or rounded (see above), we can assume that the author gave little attention to this detail. 2) A particular feature of the specimens from Sardinia, yet more expressed in the females than in the male, is the central narrowing of I-L-6. This detail is not given explicitly in Angelier’s fig. 28, eventually due to the fact that this appendage was drawn in a squeezed state. 3) A further character state in merit of future attention is the doubling of the ventral seta on I-L- 5 in all three specimens described here. In other Atractides species , this phenomenon may be observed as a rare aberration, in A. gracilipes it could be a species-specific character that may be easily overlooked. Angelier’s fig. 28 gives a single ventral seta at I-L-5.

The good agreement in size and segment length proportions of appendages demonstrates that the specimen from Corsica (with sclerotized platelets D-2/-3 and V-1) is conspecific with the female from Sardinia without sclerotized muscle attachments due to juvenile age). The lower L/H proportions in the female from Corsica are probably not representative and best explained by the fact that the palps of this specimen were squeezed during slide-mounting.

Figures

FIG. 2. — Atractides gracilipes (E. Angelier,1951), specimens from Sardinia:A-C, 1 ♂, I 1162: A, venter,partial view; B, I-L-5/6; C, palp; D-F, 1 ♀, I 1165: D, venter; E, palp; F, I-L-5/6. Scale bars: 100 µm.