Gaeolaelaps sevastianovi 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 : 10-14

Gaeolaelaps sevastianovi Trach , sp. n. ( fig. 4, 1–4 ; 5, 2–5 )

M a t e r i a l. Holotype ♀, slide N 29–07–2010, Ukraine, Lugansk Region, Melovskoj District, vicinity of Krinichnoe, near Cherepaha river (49°18ʹ N 40°05ʹ E), under elytra of Heterocerus sp. ( Coleoptera , Heteroceridae ), 29.07.2010 (V. A. Trach). Paratypes, 2 ♀, same data. The holotype and paratypes are deposited in MZ.

D e s c r i p t i o n. Female (n = 3). Dorsum ( fig. 4 , 1 ). Body large, strongly swollen. Dorsal shield elongate oval (length / width ratios of 1.6–1.8), tapering posteriorly from setae r5, weakly reticulate throughout, 269 (273–277) in length, maximum width 164 (155–164) 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), setae Px2–3 and Jx absent. Setae j1 and z1 21–23 (19–23), other setae 32–44 (32–48) long. Dorsal shield with about 10 pairs of pore-like structures. Dorsal soft cuticle with three pairs of simple setae, 25–32 (25–34) long.

Venter ( fig. 4 , 2 ). Tritosternum with a wide base, 11 (11) long, 13 (13) wide at base, 6 (6) wide at apex, with two plumose laciniae, length free for 42 (38–42) and fused basally for 4 (4). Presternal area lightly punctate, with a few transverse lines. Sternal shield 105 (105–109) long, minimum width between coxae II 69 (71–74), maximum width at the anterior part of the shield — 76 (78–80) and posteriorly of the coxae II — 99 (99–105), posterior margin rounded. Sternal shield bearing three pairs of setae 25–29 (25–29) long and two pairs of lyrifissures. Weak reticulate sculpture developed on edges of shield. Setae st4 (27 (27)) and lyrifissures iv3 located on soft cuticle. Epigynal shield wide, weakly reticulated, with simple setae st5 (25 (25–27)). Shield 78 (78–80) in length, maximum width — 42 (42–46). Pair of paragenital platelets is located near the epigynal shield. Anal shield subtriangular, 48 (44–46) long, 46 (46) 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 — 19–21 (19–21), postanal seta — 21 (21). Soft cuticle with seven pairs of simple setae (JV1–5, ZV1–2), 21–25 (21–25) long. Parapodal platelets thin, fused with peritrematal shields. Peritrematal shields very short, extending to posterior level of coxae III, 46 (44–48) long. Peritremes very short, reaching only to anterior level of coxae IV, 21 (21–23) long, 13 (13) wide near the middle. Spermathecal structures are indiscernible.

Gnathosoma ( fig. 4, 3–4 ). Tectum not discernible. Subcapitulum ( fig. 4 , 3 ) with 6–7 (6 in holotype, 7 in two paratypes) rows of deutosternal denticles. Rows with 10–15 denticles. Subcapitulum 80 (80–84) in width. Corniculi horn-like. Hypostomal setae simple, length of setae pc — 15 (15), hp1 — 21 (19–21), hp2 — 19 (17–19), hp3 — 19 (19–21). Palps 103 (101–103) 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 74 (71–74) in length, with fringed arthrodial corona, fixed digit of chelicerae with two teeth and pilus dentilis ( fig. 3 , 4 ). Movable digit of chelicerae with two large uniform teeth, 32 (32) long.

Legs( fig.5, 2–5 ). Legs thickened and stocky.Length of legs: I —273–277(269–277), II — 218–223 (210–218), III — 193–197 (189–193), IV — 239–244 (244–252). 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)– 8 (2–2/1–2/ 0 –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)– 8 (2–2/1–3/0– 0)– 9 (2–1/1– 3/1– 1)–18(3–3/3–1/1–2/2–3). Tarsus I with numerous setae. All leg setae simple, smooth, some slightly thickened.

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

— 37 pairs of simple setae the dorsal shield;

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

— 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), genua III with only eight setae (pv is lacking), genua IV with only eight setae (pl is lacking), tibia IV with only nine setae (one pl is lacking).

By the short peritremes, G. sevastianovi Trach , sp. n. is similar to G. carabidophilus , G. dubininae , G. heteroceri Trach , sp. n., G. khaustovi Trach , sp. n. and G. rhizotrogi .

G. sevastianovi Trach , sp. n. differs from G. khaustovi Trach , sp. n. by the shape of dorsal shield (elongate oval in G. sevastianovi Trach , sp. n., greatly elongate in G. khaustovi Trach , sp. n.), number of setae on the dorsal shield (37 pairs in G. sevastianovi Trach , sp. n., 37 pairs and one unpaired medial seta in G. khaustovi Trach , sp. n.), chaetom of dorsal soft cuticle (normal in G. sevastianovi Trach , sp. n., hypertrichous in G. khaustovi Trach , sp. n.), shape of sternal, epigynal, anal and peritrematal shields, number of pairs of lyrifissures on sternal shield (two in G. sevastianovi Trach , sp. n., three in G. khaustovi Trach , sp. n.), leg chaetotaxy (abnormal in G. sevastianovi Trach , sp. n., normal in G. khaustovi Trach , sp. n.) and other characters.

From G. carabidophilus , G. sevastianovi Trach , sp. n. primarily differs by number of setae on the dorsal shield (37 pairs in G. sevastianovi Trach , sp. n., 39 pairs in G. carabidophilus ), chaetom of dorsal soft cuticle (normal in G. sevastianovi Trach , sp. n., hypertrichous in G. carabidophilus ), shape of sternal, epigynal and peritrematal shields, number of pairs of lyrifissures on sternal shield (two in G. sevastianovi Trach , sp. n., three in G. carabidophilus ), leg chaetotaxy (abnormal in G. sevastianovi Trach , sp. n., normal in G. carabidophilus ).

G. sevastianovi Trach , sp. n. differs from G. dubininae and G. rhizotrogi by the shape of dorsal shield (elongate oval in G. sevastianovi Trach , sp. n., obovate in G. dubininae and G. rhizotrogi ), shape of sternal and peritrematal shields and other characters.

From G. heteroceri Trach , sp. n., G. sevastianovi Trach , sp. n. primarily differs by number of setae on the dorsal shield (37 pairs in G. sevastianovi Trach , sp. n., 39 pairs in G. heteroceri Trach , sp. n.), shape of epigynal and peritrematal shields, shorter peritremes and leg chaetotaxy.

By the presence only 37 pairs on the dorsal shield and presence only two pairs of lyrifissures on the sternal shield G. sevastianovi Trach , sp. n. is similar to G. ahangarani Kazemi et Beaulieu, 2014 ; G. angustiscutatus Willmann, 1951 ; G. barbarae ( Strong, 1995) ; G. genitotortus Sklyar, 2012 ; G. invictianus Walter et Moser, 2010 ; G. paraculeifer Rosario, 1981 ; G. passalus Rosario, 1981 ; G. praesternalis Willmann, 1949 ; G. queenslandicus (Womersley, 1956) ; G. rarosae Rosario, 1981 ; G. verticis (Karg, 1979) and G. vertisimilis (Karg, 1994) . From all species, G. sevastianovi Trach , sp. n. differs by very short peritremes and abnormal leg chaetotaxy.

B i o l o g y. Only three females without eggs were found under elytra on the one specimen of Heterocerus sp. (about 20 specimens of Heterocerus sp. were examined from same locality). The feeding biology of G. sevastianovi Trach , sp. n. is unknown. Probably G. sevastianovi Trach , sp. n. is associated with Heteroceridae that live along the shores of fresh waters.

E t y m o l o g y. This species is named in honour of my teacher, Professor V. D. Sevastianov, who devoted many years to training acarologists in I. I. Mechnikov Odessa National University.

Figures

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

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. 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.