A review of myrmecophilous mites of the family Microdispidae (Acari, Heterostigmatina) of Western Siberia.

Five species of myrmecophilous microdispid mites (Acari: Microdispidae) are recorded from Western Siberia, Russia. Unguidispuslasii Kurosa, 1979, Unguidispusjaponicus Kurosa, 1979, Caesarodispusminutus (Sevastianov, 1981), and Caesarodispussamsinaki (Mahunka, 1967), comb. n. are reported from Russia for the first time. Unguidispuspolyctenus (Sevastianov, 1969) and Caesarodispussamsinaki are redescribed. The keys to species of the genera Unguidispus Mahunka, 1970 and Caesarodispus Mahunka, 1977 are provided.

Introduction

The family Cross, 1965 (: ) includes 18 genera and about 115 described species (Hajiqanbar and Hosseininaveh 2014). All representatives from the genera PageBreak Mahunka, 1970, Mahunka, 1977, Cross, 1965, Mahunka, 1977, Cross, 1965, and Cross, 1965 are associated with various ants (: ) (Hajiqanbar and Hosseininaveh 2014). Most of microdispid mites are fungivorous, but the species from the genera and , associated with army ants, probably feed on their larvae and/or eggs (Kaliszewski et al. 1995). During the study of myrmecophilous mites of Western Siberia we found five species of the family belonging to the genera Mahunka, 1970 and Mahunka, 1977. The main goal of this paper is to redescribe the poorly known species (Sevastianov, 1969) and (Mahunka, 1967), comb. n. and provide new records of myrmecophilous microdispid mites from Western Siberia, as well as the keys to world species of the genera and .

Materials and methods

Mites were collected from ants or ant nests and mounted in Hoyer’s medium. The terminology of idiosoma and legs follows Lindquist (1986); the nomenclature of subcapitular setae and the designation of cheliceral setae follow Grandjean (1944, 1947), respectively. The system of follows Khaustov (2004, 2008). All measurements are given in micrometers (μm). For leg chaetotaxy the number of solenidia is given in parentheses. The studied material is deposited in the mite collection of the Tyumen State University Museum of Zoology, Tyumen, Russia. SEM photographs were made with the aid of JEOL–JSM-6510LV SEM microscope.

Systematics

Family Cross, 1965

Mahunka, 1970

Type species.

Mahunka, 1970, by original designation.

Diagnosis.

Female. Gnathosoma dorsally with 2 pairs of setae. Pharyngeal pumps 1 and 3 vestigial, pharyngeal pump 2 large, transversely striated. Prodorsum usually almost completely covered by tergite C. Cupules ia and ih small, round. Two pairs of pseudanal setae present (ps2 absent). Posterior margin of posterior sternal fig entire. Leg I distinctly shorter than leg II. Tibiotarsus with well-developed claw; eupathidia tc’-tc” situated on clear pinnaculum; setae s of tibiotarsus I present. Trochanter IV anterodorsally with short spine-like process.

The genus currently includes six species distributed in the Palaearctic region: , (Sevastianov, 1969), Sevastianov, 1981, Kurosa, 1979, Kurosa, 1979, and Kurosa, 1979. All species of the genus phoretic on ants of the genera L. and Fabricius (: ), or inhabit their nests (Hajiqanbar and Hosseininaveh 2014; Kurosa 1979).

(Sevastianov, 1969)

Figs 1 , 2 , 3 , 4

Figure 1.

(Sevastianov, 1969), female: A dorsum of the body B venter of the body.

Figure 2.

(Sevastianov, 1969), female: A leg I B leg II.

Figure 3.

(Sevastianov, 1969), female: A leg III B leg IV.

Figure 4.

(Sevastianov, 1969), female, SEM photos: A dorsum of the body B lateral view of the body C tergites EF and H D venter of the body E gnathosomal capsule F legs I and distal part of gnathosoma laterally.

Sevastianov, 1969, p. 68, fig. 2.

:

:

Redescription.

Female Length of idiosoma 190–205, width 120–135.

Gnathosoma (Figs 1, 4E, 4F). Gnathosomal capsule beak-like, about 1.5 times longer than its width. Dorsally with two pairs of smooth subequal setae (cha, chb). Dorsal median apodeme absent. Ventral gnathosoma with one pair of subcapitular setae m and a pair of oval pits situated posteromedial to bases of m. Palps with setae dFe and dGe dorsolaterally. Setae dGe slightly longer than dFe. Ventral palpal structures not evident even on SEM photos (Fig. 4F). Palps terminated with a relatively long and thin tibial claw (Fig. 4F).

Idiosomal dorsum (Figs 1A, 4A). Prodorsum almost completely covered by anterior margin of tergite C, with one pair of setae sc2, one pair of clavate and weakly barbed trichobothria sc1 with pointed apex, and one pair of large round stigmata. All dorsal shields smooth. All dorsal setae distinctly barbed; setae d and f blunt-ended, other dorsal setae pointed. Posterior margin of tergite C straight; posterior margin of tergite H with tongue-like elongation medially. Cupules ia on tergite D and ih on tergite H small, round. Lateral shields covering lateral parts of tergite D with distinct sclerotized lines (Fig. 4B). With a pair of arch-like structures anteriorly to setae f and a pair of oblique ridges connected to bases of setae e (Fig. 4C). Length of dorsal setae: sc2 12–14, c1 35–38, c2 40–42, d 36–38, e 44–45, f 35–37, h1 40–45, h2 35–37. Distances between setae: sc2–sc2 37–40, c1–c1 47–50, c1–c2 22–24, d–d 41–43, e–f 18–20, f–f 35–38, h1–h1 19–21, h1–h2 18–21.

Idiosomal venter (Figs 1B, 4D). All ventral figs smooth. All ventral setae pointed and barbed, except smooth ps3. Apodemes 1 (ap1) weakly developed and joined with prosternal apodeme (appr); apodemes 2 (ap2) well developed, arch-like, fused with appr; prosternal and sejugal (apsej) apodemes well developed; apodemes 3 (ap3) well sclerotized. Apodemes 4 (ap4) well sclerotized and long, apodemes 5 absent. Posterior margin of posterior sternal fig slightly convex in middle part. Posterior margin of aggenital fig rounded. Anterior genital sclerite (ags) bell-like, posterior genital sclerite (pgs) very small, triangular. Length of ventral setae: 1a 35–37, 1b 21–23, 2a 33–36, 2b 36–40, 3a 34–36, 3b 35–37, 3c 36–38, 4a 36–38, 4b 52–55, 4c 39–41, ps1 24–26, ps3 9–11.

Legs (Figs 2–3, 4F). Leg I (Figs 2A, 4F) distinctly shorter and thinner than leg II. Setal formula: 1–3–4–16(4). Tibiotarsus not thickened, with well-developed terminal claw situated on distinct pretarsus, tip of the claw thin. Length of solenidia ω1 11–12 = ω2 11–12 > φ1 6–7 = φ2 6–7; ω1 and ω2 finger-shaped, φ2 baculiform, φ1 clavate. Setae (u) fused into structure opposing to tarsal claw. Leg II (Fig. 2B). Setal formula: 1–3–3–4(1)–6(1). Tarsus with sickle-like, padded claws and large empodium. Solenidion ω 9–10, finger-shaped, solenidion φ 3–4 weakly clavate. Seta dFe distinctly blunt-ended. Leg III (Fig. 3A). Setal formula: 1–2–2–4(1)–6. Claws of same shape as on tarsus II. Solenidion φ 3–4 weakly clavate. Seta dFe distinctly blunt-ended. Leg IV (Fig. 3B). Setal formula: 1–2–1–4(1)–6. Tarsus long and thin, pretarsus short, with two small simple claws and small empodium. Solenidion φ 3–4, weakly clavate. Seta dFe distinctly blunt-ended.

Male and larva unknown.

Material examined.

Eight female paratypes, Ukraine, Khmelnitsk Province, vicinity of settlement Chemerovtsy, on ants Forster, 23 July 1966, coll. V.D. Sevastianov; 3 females, Russia: Tyumen Province, vicinity of Tyumen, 57°04'03"N, 65°04'12"E, on ants L., 17 August 2014, coll. A.A. Khaustov; 15 females, Russia, Tyumen Province, vicinity of Tyumen, 57°13'43.6"N, 65°28'28.4"E, on ants , 14 September 2014, coll. A.A. Khaustov.

Distribution and hosts.

This species was described from Western Ukraine from ants Forster (Sevastianov 1969). It was also recorded in northwestern Russia (Sevastianov 1978), Austria (Mahunka 1970b) from ants L., and in Hungary from ant nest (Mahunka 1987).

Remarks.

Sevastianov (1969) placed this species in the genus Sevastianov, 1969. Mahunka (1970a) transferred it to Mahunka, 1968 () which he considered as a senior synonym of . The same year Mahunka (1970b) moved this species to the microdispid genus Mahunka, 1970. In spite of this, Sevastianov (1978) retained it in the neopygmephorid genus .

The original description of of Sevastianov (1969) is incomplete, thus I made a redescription of this species. The present redescription of is based mainly on material from Western Siberia. The female paratypes available for this study are found in bad condition, yet sufficient to prove their identity with mite specimens from Western Siberia.

Kurosa, 1979

Kurosa, 1979, p. 66, figs 5–6.

Six females, Russia: Tyumen Province, vicinity of Tyumen, 57°04'03"N, 65°04'12"E, on ants PageBreak L., 17 August 2014, coll. V.M. Salavatulin; 5 females, Russia: Tyumen Province, vicinity of Tyumen, 57°09'55"N, 65°27'32"E, on ants , 31 August 2014, coll. A.A. Khaustov.

This species was described from Japan where it was found in the nests of ants and Yamauchi and Hayashida (Kurosa 1979). I recorded phoresy of this species on in Western Siberia. This is a new record for the fauna of Russia.

Kurosa, 1979

Kurosa, 1979, p. 64, figs 1–2.

Five females, Russia: Tyumen Province, vicinity of Tyumen, 57°04'03"N, 65°04'12"E, on ants , 17 August 2014, coll. V.M. Salavatulin. 2 females, Russia: Tyumen Province, vicinity of Tyumen, 57°09'55"N, 65°27'32"E, on ants , 31 August 2014, coll. A.A. Khaustov.

This species was described from Japan from the nests of ants (Kurosa 1979). I recorded phoresy of this species on in Western Siberia. This is a new record for the fauna of Russia.

Mahunka, 1977

Mahunka, 1977, by original designation.

Female. Gnathosoma dorsally with two pairs of setae. Pharyngeal pumps 1 and 3 vestigial, pharyngeal pump 2 large, transversely striated. Prodorsum usually almost completely covered by tergite C. Cupules PageBreakia and ih small, usually round. Two pairs of pseudanal setae (ps2 absent). Posterior margin of posterior sternal fig entire. Leg I distinctly shorter than leg II. Tibiotarsus without claw; pinnaculum absent; setae s of tibiotarsus I present. Trochanter IV anterodorsally without spine-like process.

The genus currently includes nine species distributed in the Holarctic region: , (Mahunka, 1967), comb. n., (Sevastianov, 1981), (Sevastianov, 1981), Khaustov & Moser, 2008, Khaustov, 2009, Mahunka, 1986, (Berlese, 1903), and Loghmani & Hajiqanbar, 2014. All species of the genus phoretic on various ants, or inhabit their nests. Loghmani et al. (2014) discussed distribution and host specificity of the genus and provided key to eight species.

(Mahunka, 1967) comb. n.

Figs 5 , 6 , 7

Figure 5.

(Mahunka, 1967), comb. n., female: A dorsum of the body B venter of the body.

Figure 6.

(Mahunka, 1967), comb. n., female: A leg I B leg II.

Figure 7.

(Mahunka, 1967), comb. n., female: A leg III B leg IV.

Mahunka, 1967, p. 241, fig. 1.

:

:

Female. Length of idiosoma 220, width 135. Gnathosoma (Figs 5–6). Gnathosomal capsule about as long as its width. Dorsally with two pairs of smooth setae (cha, chb). Setae cha slightly longer than chb. Dorsal median apodeme absent. Ventral gnathosoma with one pair of subcapitular setae m and a pair of oval pits situated posteromedial to bases of m. Palps short, with setae dFe and dGe dorsolaterally. Setae dGe slightly longer than dFe. Ventrally with tiny solenidion and accessory setigenous structure. Palps terminated with a relatively short and thick tibial claw. Palpal tibiotarsus laterally with small triangular translucent process. Pharyngeal pumps 1 and 3 small, vestigial; pharyngeal pumps II large, transversely striated (Fig. 5A).

Idiosomal dorsum (Fig. 5A). Tergite C covering only posterior part of prodorsum, which bears one pair of setae sc2, one pair of spherical and weakly barbed trichobothria sc1 and one pair of oval stigmata. Prodorsal shield with sparsely distributed small dimples. All hysterosomal tergites distinctly reticulated and with sparsely distributed small dimples. All dorsal setae lanceolate, sparsely barbed. Posterior margin of tergite C straight; posterior margin of tergite H with tongue-like elongation medially. Cupules ia on tergite D and ih on tergite H very small, round. Length of dorsal setae: sc2 32, c1 42, c2 44, d 58, e 47, f 50, h1 54, h2 46. Distances between setae: sc2–sc2 43, c1–c1 35, c1–c2 24, d–d 31, e–f 25, f–f 30, h1–h1 29, h1–h2 19.

Idiosomal venter (Fig. 5B). All ventral figs with small dimples. Posterior part of posterior sternal fig and aggenital fig reticulated. All ventral setae pointed and barbed. Ap1 well-developed and joined with appr; ap2 thin, arch-like, fused with appr; appr and apsej well developed; ap3 indistinct. Ap4 well sclerotized and long, apodemes 5 absent. Posterior margin of posterior sternal fig slightly convex in middle part. Posterior margin of aggenital fig rounded. Ags bell-like, pgs elongate, subtriangular. PageBreakLength of ventral setae: 1a 35, 1b 32, 2a 42, 2b 39, 3a 52, 3b 47, 3c 40, 4a 54, 4b 60, 4c 47, ps1 23, ps3 24.

Legs (Figs 6–7). Leg I (Fig. 6A) distinctly shorter and thinner than leg II. Setal formula: 1–3–4–16(3). Tibiotarsus not thickened, cylindrical. Length of solenidia ω1 11 > φ1 5 < φ2 10; ω1 and φ2 finger-shaped, φ1 clavate, solenidion ω2 absent. Seta k very long, slightly longer than combined genu and tibiotarsus I. Leg II (Fig. 6B). Setal formula: 1–2–3–4(1)–6(1). Tarsus with sickle-like, padded claws and large empodium. Solenidion ω 8, finger-shaped, solenidion φ 4 weakly clavate. Setae v” of femur II absent. Leg III (Fig. 7A). Setal formula: 1–2–2–4(1)–6. Claws of same shape as on tarsus II. Solenidion φ 4 weakly clavate. Seta dFe blunt-ended. Leg IV (Fig. 7B). Setal formula: 1–2–1–4(1)–6. Tarsus long and thin, pretarsus short, with two small simple claws and small empodium. Solenidion φ 4, weakly clavate. Seta dFe distinctly blunt-ended.

Male and larva unknown.

One female, Russia: Tyumen Province, vicinity of Tyumen, 57°04'03"N, 65°04'12"E, on ants L., 17 August 2014, coll. A.A. Khaustov.

This species was originally described from the Czech Republic (Mahunka 1967) where it was collected from ants . It was also recorded from Ukraine and Belarus (Sevastianov 1978). This is a new record for the fauna of Russia.

Mahunka (1967) described this species in the genus Kramer (). Later on, he replaced it to the genus Sasa, 1961 () (Mahunka 1972). Sevastianov (1978) placed this species in the genus Cross, 1965 ().

According to key to families of the superfamily provided by Khaustov and Ermilov (2011) this species undoubtedly belongs to the family by having three setae on femur I, unmodified seta PageBreakdFeI and presence of only one pair of setae on prodorsum. I placed this species in the genus based on the following combination of characters: 1) tibiotarsus I without claw, 2) leg I distinctly shorter and thinner than leg II, 3) seta s of tibiotarsus I present, 4) pharyngeal pumps 1 and 3 vestigial, pharyngeal pump 2 large, distinctly transversely striated, 5) posterior margin of posterior sternal fig entire. All of these characters well agree with diagnosis of the genus .

Unlike other known species of the genus , has only two setae on femur II (v” absent) and only three solenidia on tibiotarsus I (ω2 absent). However reduction of leg chaetotaxy was also recorded in C. klepzigi Khaustov and Moser, 2008, which has only two setae on femur I, while other species have three setae.

The original description of of Mahunka (1967) is incomplete, thus I made a redescription of this species. The present redescription of is based on material from Western Siberia. The specimens from Western Siberia are well agreed with original description of , especially having lanceolate dorsal idiosomal setae and unique reticulated hysterosomal tergites, and undoubtedly conspecific with it.

(Sevastianov, 1981)

Sevastianov, 1981, p. 28, fig. 5.

:

Eleven females, Russia: Tyumen Province, Tyumen region, vicinity of settlement Narimanovo, 57°21'56"N, 65°08'21"E, in the nest of ants (Fabricius), 30 July 2014, coll. V.A. Stolbov.

This species was described from Ukraine from ants L. (Sevastianov 1981). Khaustov (2009) redescribed it based on type material. It was also recorded from Iran from sp. (Loghmani et al 2014). This is a new record for the fauna of Russia.

1	All dorsal hysterosomal setae unmodified	2
–	At least setae on tergites C and D flattened, widened distally, and heavily barbed	3
2	Setae c1, d, and f thin and smooth, without arch-like ridges anteriorly to setae f	Unguidispus okumurai Kurosa, 1979. Japan. On Lasius hayashi
–	All dorsal hysterosomal setae strongly barbed, with arch-like ridges anteriorly to setae f	Unguidispus polyctenus (Sevastianov, 1969). Ukraine, Austria, Hungary, Russia. On Formica rufa, Formica polyctena
3	Setae h1 flattened, widened distally and barbed	4
–	Setae h1 thin, smooth, pointed	Unguidispus contematosus Sevastianov, 1981. Ukraine. On Lasius fuliginosus
4	Setae e distinctly thickened, subequal to or longer than f	5
–	Setae e not thickened, distinctly shorter than f	Unguidispus lasii Kurosa, 1979. Japan, Russia. On Lasius niger, Lasius hayashi
5	Setae h2 pointed, setae d distinctly thicker than f, trichobothria spherical	Unguidispus japonicas Kurosa, 1979. Japan, Russia. On Lasius niger
–	Setae h2 widened distally, setae d as thick as f, trichobothria pointed distally	Unguidispus stammeri Mahunka, 1970. Hungary. In ant nest.

1	Hysterosomal tergites not reticulated, femur II with three setae	2
–	Hysterosomal tergites distinctly reticulated, femur II with two setae (v” absent)	Caesarodispus samsinaki (Mahunka, 1967), comb. n. Czech Republic, Ukraine, Belarus, Russia. On Formica rufa.
2	Seta v’ of genu I not thickened, pointed	3
–	Seta v’ of genu I distinctly thickened, widened distally, strongly barbed	Caesarodispus pusillus Khaustov, 2009. Crimea. In the nest of Crematogaster schmidti
3	Seta d no more than 1.5 times longer than f	4
–	Seta d about 4 times longer than f	Caesarodispus klepzigi Khaustov & Moser, 2008. U.S.A. On Solenopsis invicta
4	Seta d of tibia IV heavily barbed, reaching beyond tip of pretarsus IV	5
–	Seta d of tibia IV smooth or weakly barbed, not reaching beyond tip of pretarsus IV	7
5	Seta d of femur IV subequal to or longer than tc” of tarsus IV	6
–	Seta d of femur IV more than 2 times shorter than tc” of tarsus IV	Caesarodispus gaius Mahunka, 1977. France. On Myrmica sabuleti
6	Setae d and f lanceolate and strongly barbed	Caesarodispus brevipes Mahunka, 1986. Hungary. In ant nest
–	Setae d and f not lanceolate, weakly barbed	Caesarodispus modestus (Berlese, 1903). Italy, Russia (Crimea). On Messor spp.
7	Posterior part of aggenital fig smooth	8
–	Posterior part of aggenital fig distinctly reticulated	Caesarodispus shandizensis Loghmani & Hajiqanbar, 2014. Iran. On Temnothorax sp.
8	Setae f distinctly longer than distance f–f	Caesarodispus minutus (Sevastianov, 1981). Ukraine, Iran, Russia. On Tetramorium caespitum, Lasius flavus, Temnothorax sp.
–	Setae f shorter than distance f–f	Caesarodispus acuminatus (Sevastianov, 1981). Ukraine. On Tetramorium caespitum