Gaeolaelaps carabidophilus Trach, 2012

Trach, V. A., 2012, Gaeolaelaps Carabidophilus N. Sp., A New Mite Species (Acari: Mesostigmata: Laelapidae) From Carabid Beetles (Coleoptera: Carabidae) From Southern Ukraine, Acarologia 52 (2), pp. 157-163 : 158-162

Gaeolaelaps carabidophilus Trach n. sp.

( Figures 1 and 2 )

Diagnosis — Body strongly swollen. Dorsal shield elongate oval, slightly narrowed posteriorly, with 39 pairs of setae, unpaired setae absent. Dorsal soft cuticle hypertrichous. Sternal shield with three pairs of lyrifissures. Epigynal shield narrow, with 7 (5 – 8) cells in the posterior area delimited by two lines forming an inverted-V and elongated longitudinal cells in the anterior part. Peritremes very short (reaching only to mid-coxa III). Fixed digit of chelicerae with 4 (4 – 6) teeth, movable digit with 2 large teeth.

Description — Female. Dorsum ( Figure 1A ). Body large, strongly swollen in all specimens, probably engorged on beetle haemolymph. Dorsal shield elongate oval, slightly tapering posteriorly from setae r4, with weak scale-like sculpture, 525 (465 – 549) in length, maximum width 256 (223 – 274) at level of setae r3 - r4. Shield with 39 pairs of simple setae (j1 - 6, z1 - 6, s1 - 6, r2 - 5, J1 - 5, Z1 - 5, px2 - 3, S1 - 5). Setae j1 (27 (25 - 30)) and z1 (40 (34 - 46)) are short, other setae 46 - 76 (42 - 80) long. Dorsal shield with about 21 pairs of pore-like structures. Dorsal soft cuticle hypertrichous, with 36 (32 – 37) pairs of simple curved setae, 63 – 84 (57 – 90) long.

Venter — ( Figure 2A ). Tritosternum 116 (105 – 126) in length, with free plumose laciniae. Base of tritosternum weakly elongated, 27 (27 – 32) long, maximum width - 19 (17 – 20). Laciniae with 35 – 39 (32 – 44) denticles. Presternal area weakly sclerotized and granulate, consists of 9 (7 – 11) elongated cells. Sternal shield 147 (143 – 155) long, minimum width 101 (95 – 103) between coxae II, maximum width at the anterior part of the shield - 151 (143 – 166) and near posterior part of the coxa II - 141 (141 – 162). Sternal shield bearing three pairs of setae 40 – 46 (36 – 46) long and three pairs of lyrifissures, iv3 located on the posterior margin of the shield. Weak cellular sculpture developed on the lateral margins of the shield. Setae st4 located on soft cuticle, 46 (38 – 50) long. Epigynal shield narrow, with 7 (5 – 8) cells in the posterior area delimited by two lines forming an inverted-V and elongated longitudinal cells in the anterior area. Shield 170 (155 – 181) in length, maximum width - 61 (53 – 65), the vertex of the epigynal shield of variable shape: rounded or slightly pointed ( Figures 1B - D ). Epigynal shield with simple setae st5, (40 (36 – 46) long. Narrow endopodal platelets located near coxae III and IV, narrow exopodal platelets adjacent to coxae IV. A pair of paragenital platelets is located near the epigynal shield (11 – 13 (8 – 16) x 3 – 4 (2 – 4)). Opisthosomatic venter with two pairs of metapodal platelets: larger inner 17 (14 – 20) x 13 (8 – 17) and smaller external 8 (6 – 13) x 5 (4 – 6). Anal shield inversely subtriangular with a rounded base, well sclerotized, 105 (88 – 122) long, 76 (71 – 92) wide, bearing pair of pores. Cribrum well-developed. Length of preanal setae - 38 (29 – 38), postanal seta - 34 (32 – 36). Soft cuticle with four pairs of pores and 12 pairs of simple setae (JV1 - 5, ZV1 - 4, UR and 2 setae of R -series), 42 – 67 (40 – 80) long. Narrow peritremal shields fused with dorsal shield near setae z1. Peritremes very short, reaching only to mid-coxa III, 76 – 78 (67 – 82) long, 11 – 12 (8 – 12) wide near the middle. Peritrematal plates uniting with podonotal shield anteriorly at level between setae s2 and s3. Spermathecal structures are indiscernible.

Gnathosoma — ( Figures 1E - H ). Tectum ( Figure 1E ) with anterior rounded and denticulate margin. Subcapitulum ( Figure 1F ) with six rows of deu- tosternal denticles. Row one with 5 (4 – 13) denticles, row two with 7 (7 – 18) denticles, row three with 11 (11 – 16) denticles, row four with 16 (13 – 16) denticles, row five with 9 (9 – 17) denticles, row six with 16 (9 – 18) denticles. Subcapitulum 137 (122 – 143) in length, 126 (118 – 134) in width. Corniculi horn-like. Hypostomal setae simple, length of setae pc - 26 (23 – 29), hp1 - 36 (25 – 36), hp2 - 23 (19 – 25), hp3 - 33 (25 – 34). Palps 168 (164 – 176) long, seta al on femur slightly thickened, seta al1 on genu strongly thickened, seta al2 on genu slightly thickened and blunt-ended. Palptarsal apotele slender, 2-tined. Chaetotaxy of palps: 2-5-6-14-15. Several setae on palpal tibia and most setae on palpal tarsus blunt-ended. Second cheliceral segment 127 (118 – 132) in length, with fringed arthrodial corona, fixed digit of chelicerae with 4 (4 – 6) teeth and pilus dentilis ( Figure 1G ). Movable digit of chelicerae with two large teeth, its length - 59 (55 – 59) ( Figure 1H ).

Legs — Length of legs (excluding ambulacrum): I - 484 (446 – 530), II - 372 (344 – 400), III - 358 (326 – 391), IV - 474 (428 – 512). Clows I - IV well developed, claws on leg I smaller than on legs II - IV. Leg I chaetotaxy (from coxa to tibia): 2-6-13(2-2/1-3/3-2)-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(2-2/1-2/1-1)-10(2-1/1-3/1-2)- 18(3-3/3-1/1-2/2-3). Tarsus I with numerous setae, including one S-shaped seta near the apex. Seta al on trochanter II, setae av on femur, genu and tibia II, setae av and pv on genu and tibia III, seta av on genu IV, setae av and pv on tibia IV thickened ( Figure 2B ). On tarsi II - IV thickened setae mv, av2, pv2, md and, especially, al1, pl1, av1, pv1. Seta pl2 on tarsi II - III also thickened. Setae pl3 and pl2 on tarsus IV very short, setae pd2 and pd3 very long.

Type material — Holotype (female, slide No 4-07-2010 /01) and 7 paratypes were collected un- der elytra of 2 specimens of Stenolophus mixtus (Herbst) ( Coleoptera : Carabidae ) (4 specimens of S. mixtus were examined), 4 July 2010, sea coast, Ukraine, Odessa province, Belgorod-Dnestrovsky district, vicinity of Zatoka (46°00’ N, 30°23’ E), col- lected by V.A. Trach.

Etymology — The new species is named " carabidophilus " referring to its association with carabid beetles.

Remarks — The new species belongs to the genus Gaeolaelaps (following the concept of genus as defined by Beaulieu (2009)), because it is characterized by dorsal shield with 39 pairs of simple setae, sternal shield longer than its width, presternal area weakly sclerotized, epigynal shield tongueshaped, ventral hypertrichy absent, tectum with anterior rounded and denticulate margin, six rows of deutosternal denticles, well-developed chelatedentate chelicerae and normal laelapid leg setation.

The new species differs from species of other laelapine mite genera associated with beetles ( Coleolaelaps Berlese, 1914 and Hypoaspis Canestrini, 1884 ) by the absence of long setae on the dorsal shield and on some leg segments, number of dorsal setae and other characters ( Joharchi and Halliday, 2011).

Differential diagnosis. Gaeolaelaps carabidophilus Trach n. sp. differs from all congeners by the following combination of characters:

• dorsal soft cuticle hypertrichous;

• very short peritremes (reaching only to midcoxa III);

• dorsal shield with only 39 pairs of setae;

• sternal shield with 3 pairs of lyrifissures.

By the hypertrichous dorsal soft cuticle, Gaeolaelaps carabidophilus Trach n. sp. is similar to G. millipedus Rosario, 1981 and G. angustiscutatus (Willmann, 1951) . It differs from the first species by shorter dorsal shield, longer dorsal setae, lack of unpaired setae on the dorsal shield, sternal shield with 3 pairs of lyrifissures, short peritremes (in G. millipedus , longer dorsal shield, shorter dorsal setae, dorsal shield with some unpaired median setae, sternal shield only with 2 pairs of lyrifissures, peritremes of normal length). G. carabidophilus Trach n. sp. differs from G. angustiscutatus by the shape of dorsal shield, longer dorsal setae, length of peritremes (very short in G. carabidophilus Trach n. sp. and of normal length in G. angustiscutatus ), shape of the tectum and digits of the chelicerae (4 (4 - 6) teeth on fixed digit, 2 teeth on movable digit in G. carabidophilus Trach n. sp., and about 10 on both digits in G. angustiscutatus ).

Two more species of the genus Gaeolaelaps also have shortened peritremes - G. nolli (Karg, 1962) and G. similisetae (Karg, 1965) . G. nolli also has chelicerae similar in shape to G. carabidophilus Trach n. sp. These species clearly differ from G. carabidophilus Trach n. sp. By the shape of dorsal shield (suboval in G. nolli and G. similisetae , elongate oval and slightly narrowed posteriorly in G. carabidophilus Trach n. sp.), shorter dorsal setae (for example, in G. nolli and G. similisetae dorsal setae j2 - 4 not reaching to base of next row setae, in G. carabidophilus Trach n. sp. j2 - 4 always reaching to base of next row setae), shorter peritremes (in G. nolli and G. similisetae , peritremes ending near the middle of coxae II, in G. carabidophilus Trach n. sp., peritremes ending near the middle of coxae III).

By the shape of dorsal shield, G. carabidophilus Trach n. sp. is also similar to a group of species which have dorsal shield tapering posteriorly ( G. angustiscutatus , G. angusta (Karg, 1962) , G. fishtowni Koehler and Ruf, 1993 , G. queenslandica Womersley, 1956 ). Females of G. angusta , G. fishtowni and G. queenslandica have peritremes of normal length, a large spur-like seta on femur II (only slightly thickened in G. carabidophilus Trach n. sp.) and lack dorsal hypertrichy. A comparison with G. angustiscutatus has been given above.

The morphology of the new species confirms the opinion of Beaulieu (2009) that many of arthropodassociated mites species have rare or unique characteristics of Gaeolaelaps .

Figures

FIGURE 1: Gaeolaelaps carabidophilus Trach n. sp.: A – idiosoma, dorsal view; B-D – variety of shape of epigynal shields; E – tectum; F – subcapitulum and palp; G – movable digit of chelicerae; H – fixed digit of chelicerae. Scale bar: A-D 200 µm, E-H 100 µm.

FIGURE 2: Gaeolaelaps carabidophilus Trach n. sp.: A – idiosoma, ventral view; B – leg IV. Scale bars 200 µm.