Atractides clavipes Lundblad, 1954

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 : 744-746

Atractides clavipes Lundblad, 1954

MATERIAL EXAMINED. — Corsica. F 27a, 1 ♂ ; F 61, 1 ♀; F 77, 2 ♀♀; F 80, 1 ♀. Sardinia. I 368, 1 ♀; I 1152, 1 ♀; I 1153, 1 ♂, 2 ♀♀, 2 dn ( MNHN) .

Corsica. F 61, 2 ♀♀ ; F 77, 1 ♀. Sardinia. I 1153, 2 ♂♂, 1 ♀ ; I 1161, 1 ♀; I 1168, 1 ♂; I 1171, 1 ♀; I Pusch 43, 1 ♀ ( Coll. RG) .

DISTRIBUTION. — Western and Central Europe (Mediterranean, Iberian peninsula to Alps), very rare. First records from the area covered.

HABITAT. — Crenophilous. Weakly seeping rheohelocrenes, low order streams, preferably at middle altitudes, in the area covered from 250 to 1000 m.

REMARKS

In my revision of the genus ( Gerecke 2003), based on type material, I stated that A. tenerifensis Lundblad, 1962 , could be distinguished from A. clavipes on the base of the male idiosoma sclerotization (muscle insertions smooth, sclerotized in A. clavipes ), shape of I-L-6 (relatively longer, L ratio I-L-5/6, 1.1-1.2, in A. clavipes 0.9, and more slender) and position of the sword seta of P-4 (near proximoventral, in A. clavipes near distoventral seta). Unfortunately, I reversed this information in the key for males (loc. cit. p. 355) where erroneously a relatively long I-L-5 is attributed to A. clavipes , a shorter one to A. tenerifensis . For measuring the L/H ratio I used the “HB value” (central height) which is not really suitable in a segment continuously thickened from base to tip. If the L/maximum H ratio of the segment is calculated, a range of 3.7-3.9 results for A. tenerifensis , of 2.8-3.2 for A. clavipes . In the latter character, both sexes of the A. clavipes - populations from Sardinia and Corsica are typical (L/H ratio 3.0-3.5 – in males 118-120/35-40, in females 135-155/40-55), the segment is furthermore characteristic in a proximally concave, distally protruding ventral margin (in A. tenerifensis straight from base to tip). Instead, the L ratio I-L-5/6 (0.96- 1.10) is generally higher than in the type series and probably not generally suitable for distinguishing the species from A. tenerifensis (1.10-1.20). As the dorsal sclerites of males are little extended, it is well possible that juvenile specimens with unsclerotized muscle insertions may also exist. In most cases, the sword seta on P-4 is located near the distoventral seta as described for A. clavipes , but occasionally it may be placed halfway between ventral setae, or asymmetrically, near the proximal seta on one side, near the distal one on the other.

Atractides corsicus E. Angelier, 1954 ( Fig. 1 )

MATERIAL EXAMINED. — Corsica. MNHN Paris, 4 ♀♀ syntypes, all labelled “ Atractides nodipalpis corsicus E. Ang. ♀ ”, numbered by Angelier as follows:

No. 2337. [the name “ nodipalpis ” later cancelled] “Tavignano Pont de l’ I.C. 40 ( Corse), 23.VIII.1950 ” (F Ang 20); state: Mounting medium dried, leaving only remnants surrounding the mounted parts; idiosoma in toto, ventral view, squeezed; gnathosoma and one I-L detached, one palp in situ, the other not found (MNHN-Ac1186). (Observations: integument lineated, Vgl-1+2 fused; I-L-5 dL 250, vL 140, HA 75, HB 80, HC 110, distance S-1-2, 55, L/W S-1, 130 /12, S-2, 90 /21; L I-L-6, 210, HA 30, HB 25, HC 27. P-2 distoventral margin convexly protruding; P-4 sword seta halfway between ventral setae). No 2338. [the name “ nodipalpis ” later cancelled] “Taravo Pont d’Abra ( Corse) 22.VIII.1950 ” (Ang 38); state: Mounting medium dried, idiosoma in toto, ventral view, squeezed; gnathosoma and one I-L detached, one palp and one chelicera in situ, the other palp and chelicera detached (MNHN-Ac1187). (Observations: integument lineated, postgenital area unclear; I-L-5 dL 250, vL 165, HA 67, HB 70, HC 105, distance S-1-2, 52, L/W S-1, 135 /13, S-2, 82 /20; L I-L-6, 198, HA 24, HB 18, HC 22. P-2 distoventral margin convexly protruding; P-4 sword seta halfway between ventral setae).

No. 2342. “ Golo Ponte Castirla ( Corse) 15.VIII.1950 ” (Ang 6) ; state: juvenile specimen with distorted appendages, idiosoma in toto, ventral view, squeezed, right I-L-2-6 detached, wrinkled, gnathosoma detached and folded, one palp undestroyed, in lateral position (MNHN-Ac1188). (Observations: Integument lineated, Vgl-1+2 fused; I-L-5 dL 225, vL 135, HA-C not measurable, distance S-1-2, 50, L/W S-1, 125 /-, S-2, 90 /18; L I-L-6, 180, HA 25, HB 15, HC 20. P-2 distoventral margin convexly protruding; P-4 sword seta halfway between ventral setae). No. 2345b. “ Type ”, “Ruis. Crioscia Ospédale ( Corse) 18.VIII.1950 ” (Ang 44) ; state: only one I-L and gnathosoma, sagitally cut into two parts, one with palp, the other with palp and chelicerae, all slightly squeezed (MNHN- Ac1189). (Observations: integument and postgenital area unclear; I-L-5 dL 260, vL 170, HA-C not measurable, distance S-1-2, 42, L/W S-1, 120 /8, S-2, 100 /13; L I-L-6, 190, HA 30, HB 20, HC 25. P-2 distoventral margin not protruding; P-4 sword seta near distal seta).

Corsica. F 23, 2 ♂♂, 1 ♀ ; F 44h, 1 dn. Sardinia. I 340, 1 ♂ ; I 349, 1 ♂; I 352, 1 ♂, 1 ♀; I 379, 3 ♂♂; I 386, 1 ♀; I 389, 1 ♂; I 1165, 1 ♂; I 1165 Int , 2 ♂♂, 2dn ( MNHN) .

Corsica. HM 62 , 1 ♀ ( Coll. HM). Sardinia. I 340, 2 ♀♀ ; I 352, 2 ♂♂; I 379, 2 ♂♂, 1 ♀; I 386, 1 ♀; I 389, 1 ♂, 13 ♀♀ ( Coll. RG) .

PUBLISHED RECORDS. — (sites documented by type material: Ang 6, Ang 20, Ang 38, Ang 44) Corsica. Ang 4, 1 ♀ ; Ang 6, 1 ♀ ; Ang 13, 1 ♀ ; Ang 20, 1 ♂, 3 ♀♀ ; Ang 22, 1 ♀ ; Ang 24 (no specimen numbers specified); Ang 37, 1 ♀ ; Ang 38, 1 ♀ ; Ang 44, 3 ♀♀ (E. Angelier 1954b) ; I benf 74 “ Atractides sp. ”, 1 ♂ ( Gerecke & Di Sabatino 2013); Corte, R. Restonica (affl. Tavignano) (no specimen numbers specified) ( Giudicelli 1970); Porto, middle course (200-1000 m) (no specimen numbers specified) ( Santucci 1971).

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

HABITAT. — Rhithrobiont. Middle order streams, preferably in the macchia vegetation belt at middle and low altitudes, in the area covered from 20 to 1000 m.

REMARKS

Of the originally 15 syntypes, Angelier had probably selected several, including the only male, for a separate type collection. This reference collection went lost (Angelier, pers. comm.). During the early stage of his scientific activities, he used to mount selected specimens on two slides (idiosoma, generally labelled “a”, resp. gnathosoma and selected appendages, labelled “b”). Obviously slide 2345a ended up with the lost material.

The remaining slides allow to correct the interpretation of Angelier’s description by Gerecke (2003) in two important points: 1) the integument of A. corsicus is distinctly lineated, not striated; 2) Vgl-1+2 are fused.

Furthermore, it is probable that the syntypes on which Angelier based his description represented a mix of two species (female P-2 distoventrally protruding or not, P-4 sword seta between ventral setae or near distoventral seta).

As Atractides females display much less characters suitable for species definition in view of the bad conservation state of the syntypes, I renounce to a lectotype designation.In the following,the specimens 2337-2338 and 2342 are used in comparison with newly collected populations for a redescription and better founded definition of A. corsicus .

REDESCRIPTION

Both sexes

Integument lineated, muscle insertions unsclerotized, glandularia small, round; coxae in three groups, posteromedial margin Cx-I+II broadly rounded, posterior margin of Cx-IV in mature specimens slightly irregular due to a narrow border of secondary sclerite. I-L-5 elongate subrectangular, with ventral and dorsal margins slightly diverging from base to S-1 insertion, in the extended area between S-1 and -2 subparallel; S-1 long and slender, distally equally narrowed, tip slightly truncated, forming a fine denticle on the inner side; S-2 distinctly shorter, the inner margin strongly protruding in basal third, tip bluntly pointed. Excretory pore smooth, Vgl-I+II fused. Gnathosoma without particularly projecting rostrum, palp with sexual dimorphism; P-4 with maximum H near distoventral seta, sword seta between ventral seta insertions, ventral sectors nearly equal in length.

Males

Idiosoma L/W 500-650/360-430, venter: Fig. 1A ; coxal field L/W 290-345/330-390; Cx-I+II medial L 95-120, lateral L 185-225, W 250-310. I-L-5/6: Fig. 1C ; I-L-5 dL/vL 155-195/105-133, ratio 1.5- 1.6; HA 44-49, HB 48-56, HC 60-80, ratio dL/ HB 3.3-3.7; S-1 L/W 88-110/6-9, ratio 11.1-14.7; S-2 L/W 68-81/9-11, ratio 6.9-7.9; distance S-1-2, 23-38, L ratio S-1/-2, 1.2-1.4; I-L-6 dL 125-160, HA 19-24, HB 15-18, HC 15-18; ratio dL/HB 7.1- 9.7; dL ratio I-L-5/6, 1.23-1.29. Genital field L/W 77-90/85-100, rounded, anterior margin equally convex or with a slightly protruding medial extension, posterior margin with a shallow medial indentation that may be filled with a slightly protruding area of porose secondary sclerite; gonopore L 60-65, acetabula in a curved line, surrounded by about 20 pairs of setae (fine, hair like laterally, longer and stronger medially and at posteromedial edge). Palp ( Fig. 1C ) total L 265-316; L/H (ratio, rel. L [%]) P-1, 26-35/28-30 (1.0-1.3, 10-11); P-2, 63-75/58-65 (1.1-1.2, 22-25); P-3, 55-68/43-50 (1.2-1.4, 21-23); P-4, 88-105/34-39 (2.5-2.8, 32-33); P-5, 30-35/10-14 (2.4-3.3, 11-12); L ratio P-2/P-4, 0.71-0.78; P-3/P-4, 0.63-0.70. P-2 with a strongly developed, apically rounded (sometimes finger-like narrowed) distoventral projection; P-3 relatively short and stout, ventral and dorsal margins diverging, distoventral edge little sclerotized; P-4 with dense cover of fine, hair-like setae, sword seta in segment centre.

Females

Idiosoma L/W 480-900/390-750, venter: Fig. 1D ; coxal field L/W 340-435/390-590; Cx-I+II medial L 120-130, lateral L 230-270, W 335-440. I-L-5/6: Fig. 1F ; I-L-5 dL/vL 225-260/130-155, ratio 1.7; HA 58-63, HB 60-69, HC 100-118, ratio dL/ HB 3.6-4.2; S-1 L/W 130-145/9-11, ratio 12.8-16.3; S-2 L/W 90-105/13-16, ratio 6.5-7.2; distance S-1-2, 48-58, L ratio S-1/-2, 1.3-1.4; I-L-6 dL 188- 225, HA 23-26, HB 16-19, HC 16-21; ratio dL/ HB 10.7-12.9; dL ratio I-L-5/6, 1.16-1.28. Genital field L/W 120-180/120-175, prae- and postgenital sclerites strong, genital plates L/W 90-108/28- 36, weakly curved, anteriorly pointed, posteriorly rounded, bearing about ten pairs of fine, hair-like setae. Palp ( Fig. 1E ) total L 355-403; L/H (ratio, rel. L [%]) P-1, 35-40/30-34 (1.1-1.2, 10); P-2, 78-90/58-65 (1.2-1.6, 21-23); P-3, 90-113/43-48 (2.1-2.4, 25-28); P-4, 110-123/30-30 (3.5-4.1, 30-32); P-5, 38-40/13-14 (2.9-3.0, 9-11); L ratio P-2/P-4, 0.61-0.73; P-3/P-4, 0.82-0.92. P-2 distoventral margin considerably bowed out in its distal part; P-3 and -4 long and more slender than in males, P-4 sword seta closer to distoventral seta.

REMARKS

In all important features, the newly collected populations agree with the original description of A. corsicus and/or the information obtained from the study of the type material (integument structure, excretory pore area, L proportions of segments). Differences emerging from the comparison of L/H proportions of I-L or palps are probably due to squeezing of appendages in Angelier’s slides. Furthermore, from a comparison between S-1/-2 of syntypes (with truncated resp. rounded tips) and Angelier’s figs 93/97 (with pointed tips) results that he did not take care of this morphological detail. As stated earlier ( Gerecke 2003), A. corsicus is phylogenetically far distant from A. nodipalpis of which it was considered a subspecies by Angelier. The combination of heteromorphic setae S-1/2, an unsclerotized excretory pore, fused Vgl-1+2, a rounded anterior male genital field margin is unique within Western Palaearctic Atractides species. Atractides lunipes Lundblad, 1956 , a species similar in the combination of fused Vgl-1+2 and a large interspace S-1-2, differs in longer setae S-1-2, a more slender and more strongly curved I-L-6, and lineated integument.

A re-examination of a specimen published by Gerecke & Di Sabatino (2013) without species identification from site I benf 47 demonstrates that it represents a further record of A. corsicus .

Figures

FIG. 1. — Atractides corsicus E. Angelier, 1954, specimens from Sardinia: A-C, 1 ♂, I 389: A, venter; B, I-L-5/6; C, palp; D, 1 ♀, I 379, venter, partial view; E, F, 1 ♀, I 379: E, palp; F, I-L-5/6. Scale bars: 100 µm.