Gaeolaelaps gillespiei, Beaulieu, Frédéric, 2009

Beaulieu, Frédéric, 2009, Review of the mite genus Gaeolaelaps Evans & Till (Acari: Laelapidae), and description of a new species from North America, G. gillespiei n. sp., Zootaxa 2158, pp. 33-49 : 38-44

Gaeolaelaps gillespiei sp. nov.

( Figures 1–11 )

Material examined. Holotype: Female. Canada, British Columbia, Sidney, ex. roots and soil of wilting gerbera plants, 15 April 1982, Dave Gillespie. Paratypes: 3 females, 2 males, same data as holotype; 3 females, Sidney, ex. sawdust growing media in greenhouse, 4 May 2005, Don Elliott; 21 females, 5 males, reared from culture originated from specimens collected from potted Gerbera jamsonii Hook. that were damaged by fungus gnats, Sidney, 1984, Dave Gillespie.

Diagnosis. Female dorsal shield suboval with 39 pairs of setae and 1–3 additional unpaired setae in the median area between J2–3 and between J3–4; setae px2–3 present between J and Z series; setae on shield long and slender. Seven pairs of marginal setae (r6, R1–6) in soft lateral cuticle. Peritremes extending to level of j2 and past acetabulum I. Sternal shield reticulated throughout except smooth postero-medially. Presternal area weakly sclerotized, notched anteriorly. Epigynal shield flask-shaped, relatively small, separated from the anal shield by about the length of the anal shield; reticulated throughout with larger cells behind two diagonal lines forming an inverted-V. Tectum with anterior margin rounded and denticulate. Subcapitulum with six rows of 11–34 deutosternal denticles; hypostomal seta h3 elongate and posterior to h2. Fixed digit of female chelicera with 7–10 teeth of irregular size, and male fixed digit with 11–15 small to minute teeth. Palp genua with tips of setae al1 trifurcate. Setae on legs simple and slender except the following setae thickened and/or spine-like: seta al on trochanter II, dorsal seta on trochanter IV, av2 on femur II, pd on femur III (slightly thickened), pd on femur IV, av1 on genua III–IV, pv1 on tibia II (slightly thickened), av1 and pv1 on tibia III–IV, most setae on telotarsi II–IV; pd2 and al2 on tarsus IV slender and elongate. Spermatodactyl relatively long, tip tapering sharply and bent ventrally.

Female. Dorsal idiosoma ( Fig. 1 ). Dorsal shield (600–672 long × 328–368 wide) suboval, reticulate throughout, bearing 39 pairs of setae and 1–3 unpaired setae: 22 pairs (j1–6, z1–6, s1–6, r2–r5) in podonotal region and 17 pairs (J1–5, Z1–5, px2–3, S1–5) in opisthonotal region and usually 2 (rarely 1 or 3) additional unpaired setae (Jx) in the median area between J2–3 and between J3–4; all setae simple (although J4–5 and Z5 are sometimes inconspicuously barbed, Fig. 1 inset), slender and long (49–83), except j1 (30–36) and z1 (35–43) shorter; setae s1, J1–5, Jx, and px2–3 tend to be slightly shorter (55, 49–63) than other setae, and j3–4, z3–4, s3–5 tend to be the longest (73, 66–83). Marginal setae r6 and R1–R6 relatively short (37, 30–53), in soft lateral cuticle. Peritrematal shield smooth, limited to a narrow band of varying width (3–16) bordering the peritreme on the side neighbouring the dorsal shield, free posteriorly, narrowly fused to dorsal shield near z1, bearing six pairs of discernible pore-like structures (apparently at least three lyrifissures ‘ ip’, and two or three gland pores ‘ gp’; see also male in Fig. 10 ); peritreme extending to level of j2. Dorsal shield with 21 pairs of discernible pore-like structures, of which five or six (three or four podonotal, two opisthonotal) appear secretory (gland pores ‘ gd’, Fig. 1 ) and at least 15 non-secretory (lyrifissures); the gland pore anterolaterad seta px2 is conspicuous and surrounded by a lacuna (cell-like border); the other opisthonotal pore, laterad seta S5, is similar although appears less conspicuous because the shield surface is more oblique near the edge; other gland pores minute. Gland pores on the dorsal shield can usually be distinguished from lyrifissures by their deeper structures and their sac-like invaginations and diverticula at high magnification.

Ven t ra l idiosoma ( Figs 2–3 ). Tritosternum with plumose laciniae (85–92), apparently fused proximally for 5–7 from base apex (transversal line) to a fringe of 12–14 denticles, columnar base (32–37 long) ( Fig. 3 ). Sternal shield (length 127–141), narrowest width between coxae II (95–100) ( Fig. 2 ), broadest between coxae II–III (144–170), ratio length / width 1.27–1.42, with narrow, extended arms flanking coxae II anteriorly, often obscure; reticulated throughout except smooth in postero-median region where overlapped by hyaline anterior margin of epigynal shield, cells elongate and compressed in median anterior area; shield bearing long, slender setae st1–3 (47–50, 52–59, 47–53, respectively), and lyrifissures iv1–2; posterior margin more or less straight, with a pair of minute pits near the median line (sometimes not discernible). Presternal area weakly sclerotized, lineate and lightly granulate, notched medially ( Fig. 2 , see also male, Fig. 10 ). Setae st4 (51–56) and lyrifissure iv 3 in soft cuticle; endopodals mediad coxae III–IV, angular, separate from sternal shield. Epigynal shield (full length 210–230; 95–110 from level of st5 to posterior tip) with hyaline anterior margin broadly rounded, reticulate throughout, with 6–8 larger cells in the posterior area delimited by two lines forming an inverted-V (only four cells if longitudinal divisions are not discernible), narrowest width between coxae IV (73–82), and oval posteriorly (maximum width 106–115), bearing setae st5 on margins, and flanked by pair of lyrifissures iv5 (= pst5) on soft cuticle near st5. Narrow endopodal platelet present mediad coxae III–IV. Narrow exopodal plate surrounding coxae IV, and small exopodal plate between coxae II and III. External, primary (27–30 × 5–8) and inner (9–20 × 3–4) metapodal platelets narrow; paragenital platelet narrow, beside seta ZV1 ( Fig. 2 ). Anal shield (85–103 × 78–94 wide) inversely subtriangular, lineate, with post-anal seta (44–49) longer than para-anal setae (33–36); cribrum with dense field of spicules. Soft cuticle with long (most 38–53), slender ventral setae JV1–5, ZV1–4, with JV5 longest (52–64), ZV3 shortest (31–39), and one pair of submarginal setae (UR) laterad ZV3–4 (or laterad R3–4 if seen dorsally) ( Figs 1–2 ).

Gnathosoma ( Figs 4–7 ). Tectum ( Fig. 4 ) with anterior medial margin somewhat rounded and denticulate. Subcapitulum ( Fig. 5 ) with six rows of deutosternal denticles, preceded anteriorly and followed posteriorly by a smooth ridge devoid of teeth; rows 2–3 with most denticles (23–34) and row 6 (basal row) with fewest (11–16); rows 4–6 usually with slightly larger denticles, and ridges of rows 5–6 extending onto genae; corniculi horn-like (51–55), extending slightly beyond palptrochanter; internal malae abutting and projecting medially, coarsely fringed laterally, more finely fringed along median projection, almost reaching tip of corniculi; labrum extending slightly beyond corniculi for 6–12 ( Fig. 5 ); hypostomal setae long and fine, inner posterior h3 longer (60–63) than anterior h1 (39–43), outer posterior setae h2 (26–29), and palpcoxal setae pc (41–43); setae h2 42–46 apart, and pc 52–58 apart. First cheliceral segment 68–88; second cheliceral segment (170–187) ending in fixed digit, bearing an offset large tooth and 1–2 small teeth subapically, followed by a large tooth at the level of a short, setiform pilus dentilis, and a row of 2–6 teeth of irregular size (the most proximal ones tend to be larger) flanked proximally by a larger tooth; dorsal seta posteriad dorsal lyrifissure; movable digit (64–67) bidentate, with fringed arthrodial corona ( Fig. 7 ). Palps (195–211) ( Figs 5–6 ) with simple setae except al on femur thickened, spine-like, al1 and al2 of genu thickened, and apically trifurcate and subspatulate respectively; setation of palp segments from trochanter to tarsus: 2-5-6-14 -15, including two dorso-distal setae on tibia apparently hollow and with narrowly rounded tip, and nine similar setae on tarsus; palp tarsal claw 2-tined, with tines tapered and flanked by a hyaline flap (not always discernible), ventral tine shorter (12–15 from the fork) than dorsal tine (18–20 from fork, 26–29 from base) ( Fig. 6 ).

Legs ( Figs 8–9 ). Excluding ambulacra, lengths of leg I 543–619, leg II 413–465, leg III 398–443, leg IV 570–628. Tarsus I with ambulacrum (28–38, including claws and pulvillus, excluding stalk) on short stalk (8–12); ambulacra II–III (41–51), IV (46–54); claws I–IV well developed. Lengths of femora I 113–128, II 66 –85, III 74 –91, IV 112–142; genua I 81 –87, II 71 –84, III 44 –54, IV 68 –74; tibiae I 94 –103, II 65 –70, III 47 –50, IV 73 –80; tarsi I 137–150, II–III 109–123, IV 162–182. Setation of leg segments I–IV normal for Laelapidae : coxae 2-2-2-1; trochanters 6-5-5-5, seta al on trochanter II and dorsal seta on trochanter IV thickened; femora 13-11-6-6, or I (2–2/1, 3/3–2) (as al–ad / av, pd / pv–pl), II (2–3/1, 2/2–1), III (1–2/1, 1/0–1), IV (1–2/1, 1/0–1), seta av2 on femur II spine-like, seta al2 tiny, thickened, seta pd on femur III slightly thickened, and seta pd on femur IV spine-like; genua 13-11-9-9, or I (2–3/2, 3/1–2), II (2–3/1, 2/1–2), III (2–2/ 1, 2/1–1), IV (2–2/1, 3/0–1), pv1 and pl1 absent on genu IV, ventral setae on genua III–IV slightly thickened; tibiae 13-10-8-10, or I (2–3/2, 3/1–2), II (2–2/1, 2/1–2), III (2–1/1, 2/1–1), IV (2–1/1, 3/1–2), ventral setae on tibiae II–IV thickened, especially on tibia IV; tarsi II–IV 18-18-18, with ad1–pd1 as very fine, apical processes, 0.7–0.9 × the length of the pretarsi, all setae on telotarsi II–III thick and/or spine-like, some with fine, tapering tip, except setae pd2, al2, and pl2 on tarsus II slender, and setae al2 and pl2 on tarsus III only slightly thickened; many setae on telotarsus IV spine-like, especially pl2 and pv2 which have blunter tips, setae pd2 (98–117) and al2 (77–88) slender and elongate ( Figs 8–9 ). Other leg setae simple and slender. Tarsus I with numerous poorly tapered and apparently hollow (sensory) setae dorsodistally of various lengths (13–55).

Male. Dorsal idiosoma. Dorsal shield (519–555 long × 271–305 wide), similar in ornamentation and setation to female except setae 71–91% length of same setae in female. Peritrematal shield fused to dorsal shield at the level of setae s1–2.

Ven tr al idiosoma ( Fig. 10 ). Holoventral shield (414–453 long × 209–235 wide) reticulated throughout, bearing long, slender setae st1–5 (33–47), JV1–3, ZV1–2 (31–44), para-anal (25–31) and post-anal (33–37) setae. Weakly sclerotized area anterior to ventral shield as in female. Metapodal platelet free ( Fig. 10 , right) or fused to ventral shield ( Fig. 10 , left). Soft cuticle with JV4 (28–36), JV5 (39–44) and ZV3–4 (23–32) and one pair of submarginal setae.

Gnathosoma . As in female except setae about 20% shorter with h1 (32–37), h2 (22–25), h3 (41–46), pc (31–34), palps (120–128), corniculi (40–44); chelicerae ( Fig. 11 ) with fixed digit (26–29) bearing an offset large tooth near apex with a row of (also offset) 2–3 minute teeth, followed by 3–6 minute teeth distal to setiform pilus dentilis, and 5–8 teeth of irregular size proximal to pilus dentilis; movable digit (43–47) with one tooth; spermatodactyl relatively long (from base of digit: 61–66; from articulation with digit, at around level of the tooth: 28–33), bending downward from the digit near apex with a ∼ 45 ° angle, to a tapered tip.

Legs. As in female, except leg segments approximately 12–20% and ambulacra 11–26% shorter than in female.

Remarks. Because of the unpaired median opisthonotal setae between the J series, this species could be placed in the schusteri species group of Karg (1979). However, it appears more closely related to G. aculeifer and relatives (e.g. G. neoaculeifer , G. oreithyiae ) because of the spine-like setae on the legs, fixed digit with serrations posterior to pilus dentilus, and numerous deutosternal denticles per row. Unpaired median setae between J setae occur sporadically in several laelapid genera and vary among individuals of some species; hence, they may have little taxonomic value beyond the species level among hypoaspidines ( Faraji & Halliday 2009).

The new species can be readily distinguished from G. aculeifer by its longer dorsal setae, mostly in the opisthonotal region ( G. aculeifer has short opisthonotal setae), and by the two unpaired median setae between J2–4. It also differs from G. aculeifer by the following characters: dorsal setae smoothly tapering (some setae in G. aculeifer are sword-shaped, i.e. they have nearly parallel sides and taper mostly near tip, making them look thicker), dorsal shield parallel-sided from setae r3 to S2 (slowly tapering from r 3–4 in G. aculeifer ), distance between j6 setae about 2 × distance between j5 setae (about equal in G. aculeifer ), seta Z4 anteromediad S4 (Z4 is posterior to S 4 in G. aculeifer ); sternal shield with a smaller ratio length/width (1.3–1.4) (1.5–1.9 in G. aculeifer ); seta al1 on palpgenu with trifurcate tip (bluntly rounded in G. aculeifer ); hypostomal seta h3 posterior to h2 (h3 level with or slightly anterior to h 2 in G. aculeifer ); anteriormost (first) deutosternal row is nearly straight and is as broad or narrower than the two following rows (first row is the broadest, and is rounded or angled medially in G. aculeifer ); corniculi shorter, extending slightly beyond palptrochanter (reaching middle of palpfemur in G. aculeifer ); internal malae forming a single, median projection (2–3 additional lateral, fimbriate projections in G. aculeifer ); movable digit shorter (64–67 in female) (83–98 in G. aculeifer ), despite body size (dorsal shield length 600–672) subequal with G. aculeifer (620–740); spermatodactyl longer relative to the tip of movable digit, bending downward from digit near apex at a ∼ 45 ° angle, and tapering to an acute tip (smoothly curved towards digit in G. aculeifer , and tip more blunt); thickened setae on legs II–IV in G. aculeifer are generally thinner and more acuminate in G. gillespiei , and consistent differences are as follows: genu and tibia II with av1 simple (spine-like in G. aculeifer ), tibia II with pv1 barely thickened (spur-like in G. aculeifer ), tarsus II with ad2, al1, pl1, av1–2 and pv1–2 spine-like (spur-like in G. aculeifer ), genu III with pv1 barely thickened (spine-like in G. aculeifer ), tarsus III with al3 and pl3 slightly thickened (spine-like and spur-like in G. aculeifer , respectively), femur IV with ad2 simple (spine-like in G. aculeifer ), tibia IV with pl1 simple (spine-like in G. aculeifer ), tarsus IV with pd2 relatively thin, elongate (98–117) (shorter 80–96 and spine-like in G. aculeifer ); leg setae of G. gillespiei that are not modified are smoothly tapering to a fine tip, whereas many leg setae of G. aculeifer , especially on femora, genua, tibiae and basitarsi III–IV, are sword-shaped; legs of G. aculeifer tend to be thicker and longer relative to body size, especially leg IV, which is 1.08–1.22 × the length of the dorsal shield (0.91–0.97 × in G. gillespiei ). Also, G. aculeifer has an extra pair of gland pores postero-mediad setae z6 (absent in G. gillespiei ).

The same or additional characters distinguish G. gillespiei from other species of Gaeolaelaps or ‘ Hypoaspis’ (s. lat.). Species with long dorsal setae and unpaired median setae (Jx) such as G. singuloides ( Gu & Duan 1993) , H. spiculifer Berlese (sensu Ryke 1963), and G. mohrii ( Ishikawa 1982) appear similar to the new species but differ from it at least by their fewer teeth on the cheliceral fixed digit, the shape of sternal and epigynal shields ( mohrii ), different spines on leg II ( singuloides ), and by seta st1 on the presternal area ( spiculifer ). It could also be initially confused with H. lubrica Voigts & Oudemans (1904) and H. giffordi Evans & Till (1966) , but clearly differs from them by its serrated tectum (smooth in H. lubrica and H. giffordi ), deutosternal groove with 11–34 denticles per row (7–10 in H. lubrica and 3–10 in H. giffordi ), one ventral seta (av) on genu IV (pv also present in H. lubrica ), fixed digit with 7–10 teeth (three teeth in H. lubrica and H. giffordi ), a smaller epigynal shield (more extensive in H. lubrica and H. giffordi , almost reaching anal shield), and fewer Jx setae on the dorsal shield (at least four Jx in H. lubrica and H. giffordi ) ( Evans & Till 1966).

This species is named in honour of David Gillespie (Agriculture & Agri-Food Canada) who collected the species and encouraged its use as a predator against fungus gnats and thrips ( Gillespie & Quiring 1990). Because G. gillespiei was collected from a substrate with components that may have several sources, it is unclear whether the mite is native to North American soil or originates from overseas.

Figures

FIGURES 1 – 4. Gaeolaelaps gillespiei n. sp., female. 1, Dorsal shield; 2, Ventral idiosoma. Arrows showing endopodal platelet, (2) metapodal platelets, (1) paragenital platelet, and lyrifissure iv 5; 3, Tritosternum; 4, Tectum.

FIGURES 5 – 8. Gaeolaelaps gillespiei n. sp., female. 5, Subcapitulum and trochanter, femur and genu of palp; 6, Palp tarsal claw; 7, Chelicera, antiaxial view; 8, Left leg II, antero-lateral view.

FIGURES 9 – 11. Gaeolaelaps gillespiei n. sp. 9, Female, right leg IV, dorsal view; 10, Male, holoventral and peritrematal shields; 11, Male, chelicera, spermatodactyl, and variation in teeth on fixed digit, antiaxial view.