Asetadiptacus acarubri, Pye, Daniel R. L. & Lillo, Enrico De, 2010

Pye, Daniel R. L. & Lillo, Enrico De, 2010, A review of the eriophyoid mites (Acari: Eriophyoidea) on Rubus spp. in Britain, with a new species (Diptilomiopidae) and two new records, Zootaxa 2677, pp. 15-26 : 19-20

Asetadiptacus acarubri n. sp.

( Figs. 5 & 6 )

Female: (n=10). Body fusiform, 164 (142–234), 81 (77–86) wide. Gnathosoma projecting obliquely down, chelicerae 67 (59–72), setae d 11 (11–14). Prodorsal shield 35 (35–41), 59 (58–68) wide, frontal lobe 7 (5– 10), ornamented with a series of depressions and lines, creating a cellular pattern ( Fig.1 –, H). Tubercles sc slightly ahead of rear shield margin, 27 (26–30) apart; setae sc absent. Leg I 42 (41–44); femora 12 (11–13), setae bv absent; genua 7 (7–8), setae l 32 (29–43); tibiae 13 (12–14), setae l’ 6 (6–7); tarsi 9 (8–9), setae ft’ 22 (19–25), setae ft 27 (23–30); setae u’ 4 (4–6); solenidia 7 (6–7), knobbed distally; empodia divided, 7 (6–7), 6 rayed on each side. Leg II 40 (38–42); femora 12 (12–13), setae bv absent; genua 6 (6–7), setae l 11 (7–12); tibiae 12 (11–13); tarsi 9 (7–9), setae ft’ 5 (4–8), setae ft 28 (20–29); setae u’ 5 (4–7); solenidia 7 (6–8), knobbed distally; empodia divided, 7 (6–8), 6 rayed on each side. Coxae 1 ornamented with fine granules, coxae 2 with sparse granules and lines and dashes surrounding the tubercles. Setae 1b 14 (12–17), 13 (13–15) apart; setae 1a 14 (13–16), 13 (12–14) apart; setae 2a 57 (32–62), 29 (28–36) apart; tubercles 1b and 1a 10 (9–10) apart; tubercles 1a and 2a 9 (8–12) apart. Coxigenital region with 8 (8) semiannuli. Opisthosoma with 50 (50–59) dorsal annuli, sometimes with a weakly developed medial ridge, 79 (75–90) ventral annuli (66 (65–77) if they are counted from the posterior margin of the progenital chamber). Dorsal microtubercles small, beadlike, and sparse, often absent. Ventral microtubercles anteriorly small, beadlike, and becoming progressively more longitudinally elongate posteriorly, ventral annuli completely microtuberculate. Setae c2 37 (29–39), on annulus 17 (14–17) (4 (3–4) from behind the genital chamber), 56 (52–67) apart; setae d 56 (42–70), on annulus 31 (28–31) (18 (17–19) from behind the genital chamber), 38 (37–44) apart; setae e 55 (38–61), on annulus 49 (45–54) (36 (35–41) from behind the genital chamber), 21 (21–27) apart; setae f 37 (33–42), on annulus 69 (68–76) (56 (56–63) from behind the genital chamber), 30 (25–31) apart, 10 (9–13) from rear. Setae h2 75 (60–83), 11 (11–12) apart; setae h1 absent, represented by a small tubercle, 8 (8) apart; h2 and h1 tubercles 3 (2–3) apart. Genital coverflap ornamented with granules basally, smooth and unornamented posteriorly, 22 (17–23), 30 (28–32) wide. Setae 3a 9 (9–11), 20 (19–22) apart.

Male: (n=4). Similar to female. Body fusiform, 182 (150–198), 74 (72–79) wide. Gnathosoma projecting obliquely down, 32 (32–46), chelicerae 52 (52–65), setae d 11 (11). Prodorsal shield 33 (33–34), 55 (55–60) wide, ornamentation same as female. Tubercles sc slightly ahead of rear shield margin, 24 (23–25) apart; setae sc absent. Leg I 39 (37–40), femora 12 (11–13), setae bv absent; genua 7 (6–7), setae l 27 (27–37); tibiae 13 (11–13), setae l’ 7 (6–7); tarsi 9 (8–9), setae ft’ 19 (19–24), setae ft 27 (26–27); setae u’ 5 (5–6); solenidia 6 (6–7), knobbed distally; empodia divided, 7 (6–7), 5 rayed on each side. Leg II 37 (37–38), femora 12 (12– 13), setae bv absent; genua 6 (5–6), setae l 11 (10–12); tibiae 12 (10–12); tarsi 7 (7–9), setae ft’ 7 (5–7), setae ft 26 (24–26); setae u’ 5 (4–5); solenidia 7 (6–7), knobbed distally; empodia divided, 6 (6–7), 5 rayed on each side. Coxae ornamented same as female. Setae 1b 13 (13), 12 (12) apart; setae 1a 15 (12–15), 11 (11) apart; setae 2a 47 (41–47), 28 (23–29) apart; tubercles 1b and 1a 9 (6–9) apart; tubercles 1a and 2a 10 (9–10) apart. Coxigenital region with 9 (9) annuli. Opisthosoma with 50 (50–53) dorsal annuli, sometimes with a weakly developed medial ridge, 78 (73–79) ventral annuli (65 (60–66) if they are counted from the posterior margin of the genital chamber), microtubercles same as female. Setae c2 26 (26–36), on annulus 16 (15–17) (3 (2–4) from behind the genital chamber), 55 (46–58) apart; setae d 42 (42–62), on annulus 28 (28–29) (15 (15–16) from behind the genital chamber), 39 (33–39) apart; setae e 28 (28–54), on annulus 47 (44–47) (34 (31–34) from behind the genital chamber), 23 (20–23) apart; setae f 38 (35–40), on annulus 67 (66–70) (54 (50–57) from behind the genital chamber), 25 (25–29) apart, 12 (11–12) from rear. Setae h2 65 (60–80), 11 (9–11) apart; setae h1 absent, represented by a small tubercle, 7 (6–7) apart; h2 and h1 tubercles 2 (2–3) apart. Genital shield ornamented with fine granules, 17 (16–22), 22 (17–23) wide. Setae 3a 8 (6–8), 18 (15–19) apart.

Host plant. Rubus fruticosus .

Relation to the host. Vagrant on both leaf surfaces causing no apparent damage.

Type locality. South East of England, Kent, Tonbridge, commercial plant nursery site, 07.x.2009.

Type material. Holotype female, on one slide, and nine further paratype slides, each of one specimen, have been deposited at the Natural History Museum, London. Twenty-eight paratype slides, each of one specimen, have been retained in the collections of Fera. Five paratype slides, each of one specimen, are deposited with the second author, Bari University, Italy.

Etymology. The specific name is derived from the Latin acarus and rubrum meaning ‘mite of blackberry’.

Discussion. This is the sixth species to be described in the genus Asetadiptacus , the other five being: Asetadiptacus emiliae Carmona, 1971 from Ficus carica L. ( Moraceae ), Portugal; Asetadiptacus salvifoliae de Lillo, 1997 from Cistus salvifolius L. ( Cistaceae ), Italy; Asetadiptacus indosasae Kuang, 2001 from Indosasa crassiflora McClure (Poaceae) , China; Asetadiptacus carmonae Umapathy & Mohanasundarum, 2002 from Salacia sp. (Celastaceae), India; and Asetadiptacus phaeostictaus Huang & Wang, 2009 from Prunus phaeosticta (Hance) Maxim. (Rosaceae) , Taiwan.

Asetadiptacus acarubri was found in very high numbers with adult females, males and immature stages present, and apart from uneven ripening of the fruit caused by A. essigi , no other host symptoms were observed on the plant material examined.

Differential diagnosis. Having examined all of the original descriptions, Asetadiptacus acarubri is clearly different to the five species already assigned to this genus. However, it is most similar to A. emiliae and A. salvifoliae : A. emiliae differs by having fewer opisthosomal annuli (45 dorsal and 64 ventral), by having a different prodorsal shield pattern with fewer anterolateral cells, and by having much longer legs (leg I 55 –60, leg II 55 –56), and 5-rayed empodia; A. salvifoliae differs by having a different prodorsal shield pattern with less regularly aligned cells, by having a smaller female genital coverflap (12, 23 wide), and generally with more dorsal opisthosomal annuli (54–74).

Additional remarks. For this species, the annuli lateral to the coxae-genital region were difficult to discern and then determine which were true annuli. There were often scattered microtubercles, artifacts, and annuli joining into one, therefore the annuli could appear to be variable in number on each side. It was more consistent to count the ventral semi-annuli from the first complete semi-annulus from behind the genital chamber.

In the original generic description of Asetadiptacus, Carmona (1971) stated “This new genus differs from the close genus Diptacus by the absence of the dorsal setae, by the absence of a strong sternal ridge as a separation of the forecoxae and the abdomen has no dorsal ridge. It is characterized by divided featherclaw, all leg segments are present and the dorsal tubercles are present but no setae [sic]”. The final generic condition has been respected in A. indosasae , with the presence of sc tubercles, but the species is described as having femoral setae on leg II. The generic conditions are not fully respected in A. carmonae , which is described as having the sc tubercles absent and the femoral setae present on leg II. Both A. indosasae and A. carmonae require careful re-examination to establish their correct generic assignment, or the generic description should be revised. Based on the current generic assignment, a key to the world species of Asetadiptacus is presented below.

Figures

FIGURE 1. Digital micrographs of the prodorsal shield and coxigenital region. Acalitus essigi. Mature protogyne female. Scale bar: 10 µm.

FIGURE 5. Semi – schematic line drawings of Asetadiptacus acarubri n. sp.: A. Lateral posterior region of female; B. Lateral opisthosomal annuli; C. Lateral anterior region of female; D. Leg I; E. Empodium; F. Internal female genitalia; G. Male genital shield; H. Prodorsal shield; I. Coxigenital region of female. Scale bar: 27 µm for A & C; 20 µm for F, G, H & I; 13 µm for B & D; 4 µm for E.

FIGURE 6. Digital micrographs of the prodorsal shield and coxigenital region. Asetadiptacus acarubri n. sp. Mature protogyne female. Scale bar: 20 µm.