Aculops orlovacae, Rector, Brian G. & Petanović, Radmila U., 2012

Rector, Brian G. & Petanović, Radmila U., 2012, A new species of Aculops (Acari: Prostigmata: Eriophyidae) from Serbia on Dipsacus laciniatus L. (Dipsacaceae), a weed target of classical biological control in the United States of America, Zootaxa 3192, pp. 59-66 : 60-64

Aculops orlovacae n. sp.

( Figs 1 & 2 )

FEMALE (n = 10). Body fusiform, 266 (165–266); width 72 (57–72). Gnathosoma 23 (20–23), downcurved. Dorsal pedipalpal genual seta d 8 (6–8), seta ep 3 (3–4), chelicerae 17 (15–18). Prodorsal shield subtriangular with a short acuminate lobe over gnathosoma, 38 (35–38), 51 (46–54) wide. Prodorsal shield ornamentation: median line present on 1/3 at the base, connected with admedian lines at basal 1/3 of the proximal part; admedian lines complete and together with submedian lines connected by transverse lines forming four cells at the basal part and three cells in the middle; two cells are present at the lateral sides, and three cells are present at the distal part of the shield. Tubercles of setae sc at rear shield margin, 21 (19–22) apart, seta sc 47 (32–47). Legs with all usual segments and setae present. Leg I 38 (34–38); femur 12 (9–12), seta bv 11 (8–12); genu 5 (5–7), seta l ʺ 25 (24–31); tibia 10 (8–10), seta l ΄ 7 (7–8); tarsus 7 (5–7), seta: ft ʺ 19 (19–25), ft ΄ 17 (13–22); solenidion ω 8 (7–8); empodium 6 (6–7), simple, bilaterally symmetrical, with 7-paired rays. Leg II 34 (30–36); femur 11 (8–11), seta bv 10 (7–13); genu 4 (4–6), seta l ʺ 8 (8–11); tibia 7 (7–8); tarsus 6 (5–7), seta: ft ʺ 22 (22–25), seta ft ΄ 6 (7–10); solenidion ω 7 (7– 9); empodium 5 (5–7), simple, bilaterally symmetrical, with 7-paired rays. Coxal plates with granules and dots. Sternal line 8 (6–8); setae 1b 10 (9–11), 13 (10–13) apart; setae 1a 33 (23–34), 10 (7–10) apart; setae 2a 47 (33– 47), 28 (20–28) apart. Coxigenital area with 9 (8–10) microtuberculated annuli. External genitalia 15 (12–15), 23 (22–24) wide, genital coverflap with 12 (12–14) longitudinal ridges; setae 3a 44 (33–44), 20 (15–20) apart. Opisthosoma with 54 (47–57) dorsal annuli and 93 (87–98) ventral annuli. Dorsal annuli with rounded microtubercles, ventral annuli with bead-like microtubercles, elongated on the posterior annuli. Setae c2 51 (41–51), 63 (46–63) apart, on ventral annulus 21 (14–22); setae d 63 (44–65), 45 (30–45) apart, on ventral annulus 41 (33–42); setae e 22 (17–22), 24 (15–24) apart, on ventral annulus 63 (52–64); setae f 31 (23–32), 26 (19–26) apart, on ventral annulus 89 (82–93) or 5th annulus from rear. Setae h1 2 (2–5), 7 (5–7) apart; setae h2 60 (59–74), 12 (9–14) apart.

MALE: Unknown.

NYMPH: Unknown.

Type material. Holotype female (1102//9) and 19 paratype females, Orlovača, south of Belgrade, Serbia (Lat. 44˚42.34ʹ N, Long. 20˚24.78ʹ E), 10 May 2007, collected by the authors. The host plant, D. laciniatus , occurred in a large population within a disturbed, uncultivated area adjacent to a roadway.

Host plant. Dipsacus laciniatus L. ( Dipsacaceae ).

Relation to host. Mites are vagrant on the surface of aboveground plant parts, causing russeting of leaves.

Etymology. The specific name is derived from the location of the original collection.

Distribution. To date, only the type population of A. orlovacae n. sp. has been found, despite repeated and directed searches for this species since its discovery.

Differential diagnosis. When compared to published line drawings and measurements, Aculops orlovacae n. sp., is morphologically similar to Aculops salixis Xue, Song et Hong (2007) , described from Salix sp. L ( Salicaceae ) in Foping County, Shaanxi Province, China. Both species have similar qualitative and meristic characteristics, including but not limited to the prodorsal shield ornamentation; number of empodial rays; number of ridges on the female genital coverflap and ornamentation on the coxae. They differ, however, in the lengths of the sc, 1a, 2a, 3a, c2, and e setae; number of dorsal and ventral opisthosomal annuli and the host plant species (see Table 1). The new species is also similar to Aculops rhodensis ( Keifer 1957) as described from Salix L. ( Salicaceae ) in Newport, Rhode Island, U.S.A. Both species have similar prodorsal shield ornamentation; number of empodial rays; number of striae on the female genital coverflap; ornamentation of Leg I coxae, as well as other morphometrical characteristics. They differ, however, in the lengths of the sc, 3a, c2, d and e setae; number of dorsal and ventral opisthosomal annuli and the host plant species (see Table 1). The new species is also similar to Aculops hussongi Keifer 1966 which was described from Lupinus obtusilobus Heller (Fabaceae) , upper Kings Creek, Lassen National Park, Shasta County, California. Both species have similar prodorsal shield ornamentation; number of empodial rays; number of ridges on the female genital coverflap; ornamentation of the coxae and several other morphometrical characteristics. They differ, however, in the length of the sc, c2, and d setae; number of dorsal and ventral opisthosomal annuli and the host plant species (see Table 1).

TABLE 1. Comparison of diagnostic morphometrical and other characteristics between Aculops orlovacae n. sp., A. salixis (data from Xue et al. 2007), A. rhodensis (data from Keifer 1957) and A. hussongi (data from Keifer 1966). Measurements are given in µ m.

Aculops orlovacae n. sp. was found on a small number of D. laciniatus plants at two locations within a large field of D. lacinatus in Orlovača. No other Aculops spp. are known from host plants in the family Dipsacaceae . Viburnum L., in the plant family Caprifoliaceae , is the closest relative to Dipsacaceae that has been recorded as a host of a mite in the genus Aculops , viz. A. oblongus recorded from Austria ( Nalepa 1894). Given the generally close association between eriophyoid mites and their host plants ( Skoracka et al. 2010) and the taxonomic proximity between A. orlovacae n. sp. and A. oblongus , a differential diagnosis was also made between these two species (see Table 2 ). In addition to its original description from Austria, A. oblongus has been reported from Denmark ( Roivainen 1949), Poland ( Soika & Labanowski 2000; Skoracka et al. 2005) and Hungary ( Farkas 1965, 1966; Ripka 2007). Unfortunately, in the original description of A. oblongus , only a few quantitative data were recorded in addition to some qualitative descriptions and a line drawing. Therefore, it is difficult to compare this to A. orlovacae n. sp. in the way that other, quantitatively described species have been compared. According to Nalepa (1894), the holotype female of A. oblongus is 120 long and 40 wide; the dorsal setae (sc) are as long as the prodorsal shield; the first ventral setae (d) are very long; the second ventral setae (e) are also long and the tarsal empodium is 4-rayed. The opisthosoma has 32 annuli (no distinction made between dorsal and ventral); the genital setae (3a) are long and the accessory setae (h1) are missing. The shield ornamentation consists of one median line; one admedian line on each side and two submedian lines on each side. All mentioned lines are complete, beginning from the base and reaching the anterior edge of the prodorsal shield. The female genital coverflap has about 8 ridges. The mite is free-living on the lower surface of leaves of Viburnum lantana L. Specimens of A. oblongus from Hungary were similar to those described from Austria ( Farkas 1966). One quantitative characteristic (viz. setae sc = 26) was supplied for the Hungarian specimens ( Farkas 1966; see Table 2 ). According to Roivainen (1949), A. oblongus specimens from Denmark were larger (150–160 long and 55 wide) than those described from Austria. Specimens of A. oblongus from Poland were not described, only identified and added to the list of Polish fauna ( Soika & Labanowski 2000; Skoracka et al. 2005). In summary, Aculops orlovacae n. sp. differs in comparison with A. oblongus in body dimensions (individuals of A. orlovacae n. sp. are larger than the Austrian, Hungarian and Danish specimens of A. oblongus ); length of sc setae (which are longer than the prodorsal shield in A. orlovacae ); number of empodial rays (7 vs. 4) and number of opisthosomal annuli (differentiated into 54 dorsal and 93 ventral annuli in A. orlovacae vs. 32 annuli in A. oblongus ( Table 2 ). In addition, the prodorsal shield ornamentation is different between the two species, there are more ridges on the female genital coverflap of A. orlovacae n. sp. than on that of A. oblongus , and setae h1 are present in A. orlovacae , while absent in A. oblongus ( Table 2 ).

Characteristic Aculus orlovacae Aculus oblongus References a No indication of whether annuli were dorsal or ventral.

Figures

FIGURE 1. Semi-schematic line drawings of Aculops orlovacae n. sp.: CG. Coxigenital region of female; CS. Lateral view of caudal opisthosoma; DA. Prodorsal shield of female; em. Empodium (in detail); ES. Lateral view of annuli; IG. Internal female genitalia; SA. Lateral view of anterior region of female; L 1. Leg I (with separate scale bar).

FIGURE 2. Digital micrographs of Aculops orlovacae n. sp.: a. Prodorsal shield; b. Legs; c. Coxigenital region (internal female genitalia visible); d. Coxigenital region (female genital coverflap visible). Scale bar = 10 μm for a, b, c and d.