Caesarodispus samsinaki (Mahunka, 1967) Mahunka, 1967

Khaustov, Alexander A., 2014, A review of myrmecophilous mites of the family Microdispidae (Acari, Heterostigmatina) of Western Siberia, ZooKeys 454, pp. 13-28 : 19-24

Taxon classification Animalia Prostigmata Microdispidae

Caesarodispus samsinaki (Mahunka, 1967) comb. n. Figs 5, 6, 7

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

Brennandania samsinaki : Mahunka 1972: 82.

Petalomium samsinaki : Sevastianov 1978: 37.

Redescription.

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. Length 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 ω 1 11> φ 1 5 < φ 2 10; ω 1 and φ 2 finger-shaped, φ 1 clavate, solenidion ω 2 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.

Material examined.

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

Distribution and hosts.

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

Remarks.

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

According to key to families of the superfamily Pygmephoroidea provided by Khaustov and Ermilov (2011) this species undoubtedly belongs to the family Microdispidae by having three setae on femur I, unmodified seta dFeI and presence of only one pair of setae on prodorsum. I placed this species in the genus Caesarodispus 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 Caesarodispus .

Unlike other known species of the genus Caesarodispus , Caesarodispus samsinaki 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 Caesarodispus species have three setae.

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