Gaeolaelaps khaustovi Trach, 2016

Trach, V. A., 2016, Three New Unusual Beetle-Associated Species Of The Genus Gaeolaelaps (Acari, Mesostigmata, Laelapidae) From Ukraine, Vestnik Zoologii 50 (1), pp. 3-16 : 7-10

Gaeolaelaps khaustovi Trach , sp. n. ( fig. 3 , 1 –7; 5, 1)

M a t e r i a l. Holotype ♀, slide N 22–04–2001, Ukraine, Crimea, Yalta City Municipality, vicinity of Sovetskoe, Canyon Uch-Kosh (44°32ʹ N, 34°12ʹ E), under elytra of Bembidion sp. ( Coleoptera , Carabidae ), 22.04.2001 (A. A. Khaustov). Paratype, ♀, same data. The holotype and paratype are deposited in MZ.

D e s c r i p t i o n. Female (n = 2). Dorsum ( fig. 3 , 1 ). Body large, strongly swollen. Dorsal shield greatly elongate (length / width ratios of 2.8–2.9), tapering posteriorly from setae r4, reticulate throughout, 416 (441) in length, maximum width 147 (155) at level of setae r4. Shield with 37 pairs of simple setae (j1–6, z1–6, s1–6, r2–5, J1–5, Z1–5, S1– 5) and one unpaired medial Jx seta, setae Px2–3 absent (in holotype one seta z6 is lost). Setae j1, z1, s1 19–23 (19–23), other setae 27–38 (23–38) long. Dorsal shield with about 17 pairs of pore-like structures. Dorsal soft cuticle hypertrichous, with 32 (32–33) pairs of simple setae, 29–42 (32–46) long.

Venter ( fig. 3 , 2 ). Tritosternum with a narrow base, 23 (21) long, 15 (15) wide at base, 8 (8) wide at apex, with two free plumose laciniae, 69 (74) long. Presternal area lightly punctate, with a few transverse lines. Sternal shield 95 (109) long, minimum width between coxae II 55 (53), maximum width at the anterior part of the shield — 80 (88) and posteriorly of the coxae II — 69 (67), posterior margin of the sternal shield of variable shape ( fig. 3 , 2 , 3 ). Sternal shield bearing three pairs of setae 25–27 (25–27) long and three pairs of lyrifissures, iv3 located on the posterior margin of the shield. Weak reticulate sculpture developed on most of the surface of shield. Setae st4 (27 (25–27)) located on soft cuticle. Epigynal shield narrow, of slightly variable shape, reticulated, with unpaired seta st5 (25 (25)). Shield 149 (153) in length, maximum width — 38 (46) ( fig. 3 , 2 , 4 ). Second seta st5 on soft cuticle near the epigynal shield is absent. Pair of paragenital platelets is located near the epigynal shield. Opisthosomatic venter with two pairs of metapodal platelets: smaller inner 6 (8) x 3 (3) and larger external 17 (21) x 6 (6). Anal shield elongate-subtriangular, 88 (95) long, 53 (53) wide, bearing pair of pores, cribrum well developed, narrowly extending laterally to level of preanal setae; anus located in the center of shield. Length of preanal setae — 27 (27), postanal seta — 29 (34). Soft cuticle with eleven pairs of simple setae (JV1–5, ZV1–5, UR), 32–42 (32–44) long. Parapodal platelets free, thin. Peritrematal shields free, very short, pointed anteriorly, extending to posterior level of coxae III, 65–67 long. Peritremes very short, reaching only to anterior level of coxae IV, 29 (32) long. Spermathecal structures are indiscernible.

Gnathosoma ( fig. 3 , 5 –7). Tectum ( fig. 3 , 5 ) with smooth front edge and denticulate margins. Subcapitulum ( fig. 3 , 6) with six rows of deutosternal denticles. Rows with 8–12 denticles. Subcapitulum 90 in width. Corniculi horn-like. Hypostomal setae simple, length of setae pc — 27, hp1 — 25, hp2 — 23, hp3 — 25. Palps 149 long, seta al on femur, setae al1 and al2 on genu thickened. Palptarsal apotele slender, two-tined. Chaetotaxy of palps normal: 2–5–6–14–15. Several setae on palpal tibia and on palpal tarsus blunt-ended. Second cheliceral segment 101 in length, with fringed arthrodial corona, fixed digit of chelicerae with three teeth and pilus dentilis ( fig. 3 , 7). Movable digit of chelicerae with two different teeth: larger proximal and smaller distal, 42 long.

Legs ( fig. 5 , 1 ). Legs slender. Length of legs: I — 483, II — 395, III — 311, IV— 445. Claws I–IV well developed. Leg chaetotaxy normal for Gaeolaelaps and Laelapidae . Leg I chaetotaxy (from coxa to tibia): 2–6–13(2–3/1–2/3–2)–13(2–3/2–3/1–2)–13(2–3/2–3/1–2). Leg II–IV chaetotaxy (from coxa to tarsus): II — 2–5–11(2–3/1–2/2–1)–11(2–3/1–2/1–2)– 10(2–2/1–2/1–2)–18(3–3/3–1/1–2/2–3); III — 2–5–6(1–2/1–1/0–1)–9(2–2/1–2/1–1)–8(2– 1/1–2/1–1)–18(3–3/3–1/1–2/2–3); IV — 1–5–6(1–2/1–1/0–1)–9(2–2/1–3/0–1)–10(2–1/1– 3/1–2)–18(3–3/3–1/1–2/2–3). Tarsus I with numerous setae. All leg setae simple, smooth. On tarsi IV most setae slightly thickened ( fig. 5 , 1 ).

D i f f e r e n t i a l d i a g n o s i s. G. khaustovi Trach , sp. n. differs from all congeners by the following combination of characters:

— greatly elongate dorsal shield;

— 37 pairs of simple setae and one unpaired medial seta on the dorsal shield;

— dorsal soft cuticle hypertrichous;

— sternal shield with three pairs of lyrifissures;

— very short peritremes (reaching to anterior level of coxae IV).

By the short peritremes, G. khaustovi Trach , sp. n. is similar to G. carabidophilus , G. dubininae , G. heteroceri Trach , sp. n. and G. rhizotrogi . G. khaustovi Trach , sp. n. is very similar to G. carabidophilus in the shape of sternal and epigynal shields, presence three pairs of lyrifissures on the sternal shield and presence more than nine pairs setae on opisthogastric cuticle. G. khaustovi Trach , sp. n. differs from G. carabidophilus by the shape of dorsal shield (greatly elongate in G. khaustovi, Trach , sp. n. and elongate oval in G. carabidophilus ), number of setae on the dorsal shield (37 pairs and one unpaired medial seta in G. khaustovi Trach , sp. n., and 39 pairs setae in G. carabidophilus ), short peritrematal shields (extending to posterior level of coxae III in G. khaustovi Trach , sp. n. and fused with dorsal shield near setae z 1 in G. carabidophilus ), shape of the fixed digit of the chelicera, shape of the metapodal platelets.

From G. dubininae and G. rhizotrogi , G. khaustovi Trach , sp. n. differs by shape of dorsal, sternal and epigynal shields, by presence one unpaired medial seta on the dorsal shield, short peritrematal shields and other characters. From G. heteroceri Trach , sp. n., G. khaustovi Trach , sp. n. differs by shape of dorsal, sternal, epigynal shields and tectum, by presence 37 pairs and one unpaired medial seta on the dorsal shield (39 pairs in heteroceri Trach , sp. n.), hypertrichous dorsal soft cuticle, shorter peritrematal shields, shape of the fixed digit of the chelicera and other characters.

By the hypertrichous dorsal soft cuticle, G. khaustovi Trach , sp. n. is similar to G. angustiscutatus (Willmann, 1951) , G. carabidophilus Trach, 2012 , G. dubininae , G. elongatus Hirschmann, Bernhard, Greim et Götz, 1966 and G. millipedus Rosario, 1981 . G. khaustovi Trach , sp. n. can be readily distinguished from G. angustiscutatus , G. elongatus , G. millipedus by shape of the dorsal shields, number setae on soft dorsal cuticle (32–33 pairs in G. khaustovi Trach , sp. n., about 20 in G. angustiscutatus and G. millipedus , about 10 in G. elongatus ), shape of sternal and epigynal shields and short peritremes. A comparison with G. carabidophilus and G. dubininae has been given above.

By the presence 37 pairs and one unpaired medial seta on the dorsal shield G. khaustovi Trach sp. n. is similar to G. magkadikitus Rosario, 1981 ; G. schusteri (Hirschmann, 1966) and G. theodori (Costa, 1974) . In G. schusteri and G. theodori seta Jx located between setae J3 and J4 (in G. khaustovi Trach , sp. n. and G. magkadikitus — between J1 and J2). In addition, G. khaustovi Trach , sp. n., G. schusteri and G. theodori have sternal shield with three pairs of lyrifissures. G. khaustovi Trach , sp. n. easily distinguished from these species by having dorsal soft cuticle hypertrichous and very short peritremes.

B i o l o g y. Most Bembidion are strongly hygrophilous and live close to water, some are confined to running waters, other to shores of lakes, ponds, or the sea. Most species are primarily scavengers, but many also take living prey such as small arthropods ( Lindroth, 1985). Only two females without eggs were found under elytra on the one specimen of Bembidion sp. The feeding biology of G. khaustovi Trach , sp. n. is unknown.

E t y m o l o g y. This species is named in honour of Dr. A. A. Khaustov in recognition of his contributions to the study of the beetle-associated mites, and who collected the type specimens.

Figures

Fig. 3. Gaeolaelaps khaustovi Trach, sp. n., ♀: 1 — idiosoma, dorsal view; 2 — idiosoma, ventral view; 3 — tectum; 4 — subcapitulum and palp; 5 — chelicera; 6 — sternal shield of paratype; 7 — epigynal shield of paratype.

Fig. 1. Gaeolaelaps heteroceri Trach, sp. n., ♀: 1 — idiosoma, dorsal view; 2 — idiosoma, ventral view; 3 — tectum; 4 — subcapitulum and palp; 5 — chelicera; Ơ: 6 — chelicera.

Fig. 2. Gaeolaelaps heteroceri Trach, sp. n., ♀: 1–4 — legs I–IV, respectively.

Fig. 4. Gaeolaelaps sevastianovi Trach, sp. n., ♀: 1 — idiosoma, dorsal view; 2 — idiosoma, ventral view; 3 — subcapitulum and palp; 4 — chelicera.

Fig. 5.Gaeolaelaps khaustovi Trach, sp. n. (1) and G. sevastianovi Trach, sp. n. (2–5), ♀: 1 — leg IV; 2 — leg I (from trochanter to tibia); 3 — leg II (from femur to tibia); 4 — leg III (from femur to tibia); 5 — leg IV.