Calacarus pusillus, Pye, Daniel R. L., 2012

Pye, Daniel R. L., 2012, New eriophyoid mites (Acari: Prostigmata: Eriophyoidea) in Britain: one new genus, four new species, 19 new records and two incursions, Zootaxa 3578, pp. 43-68 : 50-53

Calacarus pusillus n. sp.

( Figs. 4–6 )

Genus sp. Chetverikov & Sukhareva 2010 Calacarus sp. Chetverikov et al. 2010

FEMALE: (n=7). Body fusiform, 163 (146–188), 72 (64–77) wide, dark purple/grey in life. Gnathosoma 44 (39–52), projecting forward and down, setae d 12 (11–13), simple. Prodorsal shield 51 (47–52), 67 (65–72) wide, ornamented with a series of lines creating a complex pattern; median line absent; lobe with lines creating two small cell like structures; submedian lines complete, forked at posterior, and connected at about half way with a transverse shallow V shaped line; a short transverse outcrop at just above sc tubercles, which then fork divergently parallel to the submedian lines, and fade, almost touching sc tubercles; each lateral margin with a large elongate irregular cell-like structure, always notched anteriorly on under side; small dashes and round microtubercles lateral to sc tubercles. Tubercles sc ahead of rear shield margin, 32 (29–33) apart; setae sc absent. Leg I 39 (39–41); femur 12 (11–13), seta bv I 16 (13–16); genu 6 (5–6), seta l ʺ 39 (39–43); tibia 12 (11–12), seta l ʹ 9 (9–11); tarsus 9 (9–10), seta ft ʹ 24 (24–27), seta ft ʺ 23 (23–29); seta u ʹ 5 (5–6); tarsal solenidion ω 8 (8); empodium simple, 6 (6–7), 5-rayed. Leg II 36 (35–37); femur 11 (11–12), seta bv 13 (13–16); genu 5 (5), seta l ʺ absent; tibia 9 (8–9); tarsus 9 (8–9), seta ft ʹ 6 (6–8), seta ft ʺ 26 (25–28); seta u ʹ 5 (5–6); tarsal solenidion ω 8 (8–9); empodium simple, 6 (6–7), 5-rayed. Coxae 1 and 2 ornamented with short lines and dashes. Setae 1b 11 (11–13), 14 (12–15) apart; setae 1a 13 (13–16), 11 (9–11) apart; setae 2a 43 (38–49), 25 (23–30) apart; tubercles 1b and 1a 11 (11–12 apart; tubercles 1a and 2a 8 (7–10) apart. Coxigenital region with 8 (7–8) annuli. Opisthosoma with 49 (49–56) dorsal annuli, almost smooth apart from one or two small beadlike microtubercles, forming 5 longitudinal wax producing ridges (1 median, 2 submedian and 2 lateral), the ridges and microtubercles fade at the posterior and are extremely tiny, almost indiscernible; 55 (49–58) ventral annuli, microtubercles small and beadlike, ventral annuli completely microtuberculate. Setae c2 32 (24–32), on annulus 3 (3), 51 (46–55) apart; setae d 63 (49–68), on annulus 16 (12–19), 33 (31–37) apart; setae e 20 (17–20), on annulus 33 (29–37), 17 (15–18) apart; setae f 21 (20–23), on annulus 49 (43–52), 22 (21–24) apart, 7 (7) from rear. Setae h2 63 (58–70), 9 (8–10) apart; setae h1 absent. Genital coverflap ornamented with 12 (12–14) short longitudinal dashes posteriorly, 21 (20–22), 25 (23–27) wide. Setae 3a 15 (13–18), 15 (14–16) apart.

MALE: (n=2). Similar to female. Body fusiform 149–151, 62 wide. Gnathosoma projecting forward and down, 37–38, setae d 10. Prodorsal shield 42–44, 57 wide, ornamentation same as female. Tubercles sc ahead of rear shield margin, same as female, 28 apart; setae sc absent. Leg I 33–36, femur 10–11, seta bv 12–13; genu 5, seta l ʺ 33–34; tibia 9–10, seta l ʹ 5–6; tarsus 8, seta ft ʹ 20–21, seta ft ʺ 23–25; seta u ʹ 4; tarsal solenidion ω 7–8; empodium simple, 6, 5-rayed on each side. Leg II 29–30, femur 10, seta bv 11–14; genu 4, seta l ʺ absent; tibia 7–8; tarsus 7–8, seta ft ʹ 3–5, seta ft ʺ 22–23; seta u ʹ 4; tarsal solenidion ω 7; empodium simple, 6, 5-rayed on each side. Coxae ornamented same as female. Setae 1b 8–10, 11–12 apart; setae 1a 12–13, 8 apart; setae 2a 34–37, 21–23 apart; tubercles 1b and 1a 9–10 apart; tubercles 1a and 2a 7–9 apart. Coxigenital region with 8 annuli. Opisthosoma with 49–51 dorsal annuli, 49–51 ventral annuli, microtubercles same as female. Setae c2 22, on annulus 1–2, 44–45 apart; setae d 49, on annulus 13, 29–30 apart; setae e 17–18, on annulus 26–29, 14–15 apart; setae f 18–19, on annulus 43–45, 19–21 apart, 6 from rear. Setae h 2 53, 7 apart; setae h1 absent. Genital shield ornamented with fine granules basally, 42–44, 57 wide. Setae 3a 14, 13 apart.

Host plant. Calluna vulgaris (L.) Hull ( Ericaceae ).

Relation to the host. Vagrant on the foliage, causing no apparent damage.

Type locality. England, North Yorkshire, York, Strensall Common (54° 2ʹ 40.2ʺ N, 1° 0ʹ 41.76ʺ W), collected by C. Malumphy, 14.vii.2009.

Distribution. England (described and recorded here), and has also been found in Russia from C. vulgaris on several occasions (Philipp Chetverikov, personal communication 2011) and was recorded as Genus sp. (Chetverikov & Sukhareva 2010) and Calacarus sp. (Chetverikov et al. 2010).

Type material. Holotype female, on one slide, and two further paratype slides, each of one specimen, have been deposited at the Natural History Museum, London. Twelve paratype slides, each of one specimen, have been retained in the collections of Fera.

Etymology. The specific name is from the Latin pusillus (masculine), meaning 'tiny' or 'small', and relates to the overall small size of the body.

Discussion. There are now over 40 described species of Calacarus with the majority originating from Asia and North America, with some from South America, Australia, and the Pacific, but C. pusillus is the first Calacarus to be described from Europe. Of these species, Calacarus carinatus ( Green 1890) , the ribbed tea mite, originally described from Camellia sinensis (L.), Sri Lanka, is the most economically important and causes russeting and blistering of tea leaves.

Differential diagnosis. Keifer (1975) characterised most Calacarus species by their dark grey to purple coloured bodies, which usually bear five dorsal white wax ridges, with the prodorsal shield ornamentation formed from a complex series of lines and "cells". When compared to the other species of Calacarus , C. pusillus is most closely related to Calacarus helus Keifer 1969 , described from Kalmia microphylla (Hook.) A. Heller (Ericaceae) , USA, and is the only other Calacarus described from plants in the family Ericaceae . Apart from inhabiting a different host, C. pusillus morphologically differs in the prodorsal shield ornamentation: C. helus has the median line present on the posterior half, whereas the median line is completely absent in C. pusillus ; the elongate lateral cells are divided into about four smaller cells in C. helus , whereas this is undivided and always distinctively notched anteriorly on the underside in C. pusillus ; also, C. helus does not have the lines parallel to the submedian lines almost touching the sc tubercles. Calacarus pusillus also differs in the number of opisthosomal annuli (69 for C. helus , 49–56 dorsal and 49–58 ventral for C. pusillus ), and in the general body length (200–220 for C. helus , 146–188 for C. pusillus ).

Calepitrimerus buxi Petanovi ć 2000

Type host and locality. Buxus sempervirens L. ( Buxaceae ), Serbia.

Distribution. England (recorded here) and Serbia (op. cit.).

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

Collection details. England, North Yorkshire, Holtby (53° 58ʹ 41.88ʺ N, 0° 58ʹ 21ʺ W), low numbers on B. sempervirens , collected by C. Malumphy, 21.v.2009.

Calepitrimerus crataegi Malandraki, Petanovi ć & Emmanouel 2004

Type host and locality. Crataegus monogyna Jacq. (Rosaceae) , Greece.

Distribution. England (recorded here), Greece and Serbia ( Malandraki et al. 2004).

Relation to the host. Vagrant on the under surface of the leaves, causing no apparent damage.

Collection details. England, North Yorkshire, Holtby (53° 58ʹ 50.16ʺ N, 0° 58ʹ 26.04ʺ W), low numbers on the underside of the leaves of C. monogyna , collected by C. Malumphy, 22.vi.2009.

Figures

FIGURE 4. Semi-schematic line drawings of Calacarus pusillus n. sp.: A. Lateral anterior region of female; B. Lateral annuli with microtubercles; C. Lateral posterior region of female; D. Full dorsal view; E. Leg I; F. Coxigenital region of female; G. Empodium; H. Internal female genitalia; I. External male genital shield. Scale bar: 50 µm for D; 25 µm for A, C, F, H & I; 12.5 µm for B & E; 5 µm for G.

FIGURE 5. Digital micrographs of Calacarus pusillus n. sp.: A. Dorsal anterior region of female; B. Coxigenital region of female. Scale bar 20 µm for both.

FIGURE 6. Digital micrographs of Calacarus pusillus n. sp.: A. Dorsal anterior region of male; B. Coxigenital region of male. Scale bar 20 µm for both.