Gaeolaelaps heteroceri 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 : 4-7

Gaeolaelaps heteroceri Trach , sp. n. ( fig. 1, 1 –6; 2, 1–4)

M a t e r i a l. Holotype ♀, slide N 11–06–2013 /01, Ukraine, Odessa Region, Kominternovsky District, vicinity of Koshary (46°39ʹ N, 31°10ʹ E), lower reaches of the Tiligul estuary (liman), shore of salt lake, under elytra of Heterocerus sp. ( Coleoptera , Heteroceridae ), 11.06.2013 (V. A. Trach). Paratypes: 15 ♀, 1 Ơ, same data; 1 ♀, Ukraine, Mykolaiv Region, Berezansky District, vicinity of Koblevo (46°39ʹ N, 31°11ʹ E), lower reaches of the Tiligul estuary (liman), shore of salt lake, under elytra of Heterocerus sp. , 18.05.2001 (V. A. Trach); 5 ♀, Ukraine, Kherson Region, Skadovsky District, Dzharylhach Island (46°02ʹ N, 32°56ʹ E), shore of salt puddle, under elytra of Heterocerus sp. , 14.08.2014 (V. A. Trach). The holotype and paratype are deposited in MZ, other paratypes in DZ.

D e s c r i p t i o n. Female (n = 6). Dorsum ( fig. 1, 1 ). Body large, strongly swollen in most specimens. Dorsal shield elongate oval (length / width ratios of 1.8–2.1), tapering posteriorly from setae r4, reticulate throughout, 319 (311–349) in length, maximum width 160 (155–185) at level of setae r3–r4. Shield with 39 pairs of simple slightly curved setae (j1–6, z1–6, s1–6, r2–5, J1–5, Z1–5, S1– 5, px2–3), setae Jx absent. Setae j1 21 (21–23), other setae 25–40 (23–46) long. Dorsal shield with about 11 pairs of pore-like structures. Dorsal soft cuticle with 7 (6–8) pairs of simple setae, 23–29 (21–24) long.

Venter ( fig. 1 , 2 ). Tritosternum with a wide base, 15 (13–15) long, 15 (15–17) wide at base, 6 (5–6) wide at apex, with two plumose laciniae, length free for 48 (44–55) and fused basally for 6 (4–6). Presternal area lightly punctate, with a few transverse lines. Sternal shield 105 (103–120) long, minimum width between coxae II 76 (74–80), maximum width at the anterior part of the shield — 90 (90–107) and posteriorly of the coxae II — 122 (111– 124), posterior margin rounded. Sternal shield bearing three pairs of setae 25–27 (23–34) long and two pairs of lyrifissures. Weak sculpture lines developed on the lateral margins of the shield. Setae st4 (25 (25–27)) and lyrifissures iv3 located on soft cuticle. Epigynal shield narrow, reticulated, with simple setae st5 (23 (21–25)). Shield 122 (111–132) in length, maximum width — 50 (46–63), the vertex of the epigynal shield rounded. T-shaped endopodal platelets located near coxae IV. Two pairs of paragenital platelets are located near the epigynal shield. Anal shield subtriangular, 57 (55–59) long, 50 (46–53) wide, cribrum well developed, narrowly extending laterally to level of preanal setae; anus located slightly anterior to mid-level of shield. Length of preanal setae — 21 (21–23), postanal seta — 24 (23–27). Soft cuticle with seven pairs of simple setae (JV1–5, ZV1–2), 23–32 (23–32) long. Exopodal platelets between coxae III–IV and parapodal platelets fused with peritrematal shields. Peritrematal shields very short, extending to posterior level of coxae II, 111 (109– 120) long. Peritremes very short, reaching only to middle level of coxae III, 44 (44–48) long, 7 (7–8) wide near the middle. Spermathecal structures are indiscernible.

Gnathosoma ( fig. 1 , 3–5 ). Tectum ( fig. 1 , 3 ) weakly sclerotised, with some weak denticles. Subcapitulum ( fig. 1 , 4 ) with 5–7 (5 in one paratype, 6 in holotype and seventeen paratypes and 7 in three paratypes) rows of deutosternal denticles. Rows with 4–8 (4–11) denticles. Subcapitulum 80 (76–88) in width. Corniculi horn-like. Hypostomal setae simple, length of setae pc — 19 (19–23), hp1 — 19 (17–25), hp2 — 15 (13–17), hp3 — 23 (19–23). Palps 118 (109–122) 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 92 (90–95) in length, with fringed arthrodial corona, fixed digit of chelicerae with two teeth and pilus dentilis ( fig. 1 , 5 ). Movable digit of chelicerae with two uniform large teeth, 48 (42–48) long.

Legs ( fig. 2, 1–4 ). Legs thickened and stocky. Length of legs: I — 315 (315–328), II — 260 (248–269), III — 218 (214–239), IV — 290 (286–302). Claws I–IV well developed. Chaetotaxy of some segments abnormal for Gaeolaelaps and Laelapidae . Leg I chaetotaxy (from coxa to tibia): 2– 5–12 (2–3/1–2/ 2 –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– 9 (1–2 /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, some slightly thickened.

M a l e. Idiosoma of single male specimen was damaged during the slide-mounting process.

Gnathosoma as in female. Second cheliceral segment 75 in length, fixed digit as in female ( fig. 1 , 6). Movable digit with one tooth; spermatodactyl relatively large.

Legs (including chaetotaxy) as in female.

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

— dorsal shield with 39 pairs of simple setae;

— very short peritremes (reaching only to middle level of coxae III);

— abnormal leg chaetotaxy: trochanter I with only five setae (ad is lacking), femur I with only 12 setae (one pv seta is lacking), femur II with only nine setae (one al seta and one ad seta are lacking).

By the very short peritremes, shape of dorsal shield, number pairs of setae on the dorsal shield, G. heteroceri Trach , sp. n. is similar to G. carabidophilus Trach, 2012 . It differs by the shape of peritrematal shields (in G. heteroceri Trach , sp. n. extending to posterior level of coxae II; in G. carabidophilus fused with dorsal shield near setae z1), by characteristics of the sternal shield (in G. heteroceri Trach , sp. n. maximum width of the shield at the anterior part and shield bearing only two pairs of lyrifissures; in G. carabidophilus maximum width of the shield at posterior part and sternal shield bearing three pairs of lyrifissures), by shape of the fixed digit of the chelicera (two digits in G. heteroceri Trach , sp. n. and four to six in G. carabidophilus ), by chaetotaxy of dorsal soft cuticle (normal in G. heteroceri Trach , sp. n. and hypertrichous in G. carabidophilus ), by leg chaetotaxy (abnormal in G. heteroceri Trach , sp. n. and normal in G. carabidophilus ).

By the presence only 39 pairs of simple setae on the dorsal shield (and always without setae Px) and presence only two pairs of lyrifissures on the sternal shield, G. heteroceri Trach , sp. n. is similar to G. aculeifer (Canestrini, 1884) ; G. farajii Nemati et Mohseni, 2013 ; G. heselhausi (Oudemans, 1912) ; G. isodentis (Karg, 1989) ; G. matinikus ( Rosario, 1981) ; G. mossadeghi Kavianpour et Nemati, 2014 ; G. nolli (Karg, 1962) ; G. orbiculatus Nemati et Mohseni, 2013 ; G. sclerotarsus (Costa, 1968) ; G. similisetae (Karg, 1965) ; G. tenuisetus ( Rosario, 1981) ; G. transversanalis (Karg, 2000) and other. From all species, G. heteroceri Trach , sp. n. differs by very short peritremes (reaching only to middle level of coxae III; in other Gaeolaelaps species peritremes normal or rare reaches to middle or to anterior margin of coxae II) and abnormal leg chaetotaxy (leg chaetotaxy in most Gaeolaelaps not described).

From G. rhizotrogi ( Mašán, 1998) and G. dubininae ( Sklyar, 2012) (incompletely described from a single female specimen, probably a synonym of G. rhizotrogi ), G. heteroceri Trach , sp. n. differs by shorter peritrematal shields, shape of dorsal (elongate oval in G. heteroceri Trach , sp. n., obovate in G. dubininae and G. rhizotrogi ), sternal, epigynal shields,shape of the fixed and movable digits of the chelicera and other characters.

B i o l o g y. Adults and larvae of Heteroceridae construct tunnels in wet sand at the edges of streams, rivers, lakes and ponds, and in brackish mud flats. There is no agreement among authors regarding the feeding habits (Vanin et al., 2005). Mites (22 females, 1 male, 8 deutonymphs, 6 protonymphs, 1 larva and about 20 eggs) were found under elytra of about 15 specimens of Heterocerus sp. on the shores of salt lake and salt puddle. The intensity of invasion (phoresy) of beetles (for females only) stood from 1 to 3. Most of females (19) were strongly swollen. The relationships — between G. heteroceri Trach , sp. n. with their hosts is not clear. Based on the some morphological characters (for example strong chelate-dentate chelicerae), parasitism (at least in an obligate form) for G. heteroceri Trach , sp. n. and other arthropod-associated Gaeolaelaps species can probably be ruled out and predation of small invertebrates in the nests of their arthropod hosts is more likely ( Kazemi et al., 2014). Probably G. heteroceri Trach , sp. n. associated with Heteroceridae that live along the shores of salt lakes and ponds.

E t y m o l o g y. The name of the new species refers to the genus name of its host beetle, Heterocerus .

Figures

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. 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. 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.