Mashkov, Kirill A. ¹ ; Khaustov, Alexander A. ² and Goncharov, Anton A. ³

¹✉ Tyumen State University, 6 Volodarskogo Str., 625003 Tyumen, Russia.
²Tyumen State University, 6 Volodarskogo Str., 625003 Tyumen, Russia.
³A.N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Leninsky pr. 33, 119071 Moscow, Russia.

2023 - Volume: 63 Issue: 4 pages: 1211-1218

ZooBank LSID: BA1AB319-AABC-42EC-926E-AD44458EF587

Original research

Keywords

Abstract

Introduction

The family Tarsonemidae represents one of the largest groups in the mite cohort Heterostigmata (Acari: Trombidiformes) and currently includes 47 genera and more than 600 described species (Khaustov et al 2022; Khaustov et al 2021; Khaustov and Abramov 2017; Lofego et al 2016; Mondal and Karmakar 2021; Seeman et al 2018; Zhang et al. 2011). Tarsonemid mites have very broad trophic preferences, they are phytophagous, mycophagous, insect parasites, parasitoids, and egg predators of mites and insects (Lindquist 1986). Some representatives of Tarsonemidae can cause significant damage to cultivated plants, for example, Polyphagotarsonemus latus, Phytonemus pallidus, and mushroom farms can be attacked by Tarsonemus myceliophagus (Hussey 1963, Lindquist 1986). Representatives of the family Tarsonemidae can be found in soil, forest litter, on various plants as phytophagous mites or trees as cohabitants feeding on fungi (Suski 1972), and on insects as parasites or phoretically dispersed species (Lindquist 1986).

The genus Floridotarsonemus was described by Attiah (Attiah 1970). Lindquist (1986) placed Floridotarsonemus into the genus Tarsonemus as a subgenus. Later Ochoa et al. (1991) shifted its status to the genus level. At present the genus Floridotarsonemus comprises five described species:

1. Floridotarsonemus evodiae Ito, 1964 was discovered in Japan (Honshu Island), and found on Tetradium ruticarpum (A.Juss.) T.G.Hartley (syn. Evodia rutaecarpa) (Ito 1964). It was later found in Korea (Cho et al. 1995) on Ilex serrata Thumb. (Chungju) and on Camellia japonica L. (Naju).
2. Floridotarsonemus scaber Attiah, 1970 was found on ''whitefly fungus'' on citrus leaves in Florida (Attiah 1970).
3. Floridotarsonemus edule Ochoa et al., 1991 was found on Sechium edule (Jacq.) Sw. in Costa Rica (Ochoa et al. 1991).
4. Floridotarsonemus kukri Mondal and Karmakar, 2021 was found on leaves of Rhododendron indicum (L.) Sweet and Cinchona officinalis L. in West Bengal, India (Mondal and Karmakar 2021).
5. Floridotarsonemus kanthali Mondal and Karmakar, 2021 was found on leaves of Artocarpus heterophyllus Lam. in West Bengal, India (Mondal and Karmakar 2021).

This article presents the first record of the genus Floridotarsonemus in Russia with a description of a new species from Krasnodar Krai.

Material and methods

The mites were collected using a Tullgren funnel from the meadow-chernozem soil of the Krasnodar Krai in field of winter wheat cultivation. The terminology follows that of (Lindquist 1986), except the ventral subcapitular seta is labelled as m (Grandjean 1944). All measurements are given in micrometers (μm) for the holotype and five paratypes (in parentheses). Mite morphology was studied using Carl Zeiss AxioImager A2 compound microscope with phase contrast and differential-interference contrast (DIC) illumination. Photomicrographs were taken with an AxioCam 506 color digital camera. Photos were merged with Helicon Focus. Vector drawings were prepared based on layered photos in Adobe Photoshop CS2 version.

Results

Systematics

Family Tarsonemidae Canestrini and Fanzago, 1877

Subfamily Tarsoneminae Canestrini and Fanzago, 1877

Tribe Tarsonemini Canestrini and Fanzago, 1877

Genus Floridotarsonemus Attiah, 1970

Type species: Floridotarsonemus scaber Attiah, 1970, by original designation

Diagnosis — To assign the new species to the genus Floridotarsonemus, we followed the diagnosis of Lindquist (1986). He proposed the following features of female: femurogenu and tibia of leg III immovably connected, thin-walled pump, enlarged pharynx occupying one-third of the gnathosomal capsule, setae sc₂ inserted on anterior half of prodorsal shield. As can be seen (Fig. 1A) , the description of the presented species does not comply with the latter feature because setae sc₂ are located in the middle of prodorsal shield. It should be noted that approaches to the system of allocation to the genus Floridotarsonemus have changed over time and at the moment there are diagnostic approaches available by Ochoa et al. (1991) and Mondal and Karmakar (2021). The features of the new species fit to the diagnoses provided by above mentioned authors, with the exception of the narrow gnathosomal capsule. Despite some contradictions, we thus consider this species belongs to the genus Floridotarsonemus.

Differential diagnosis — The female of this new species differs from all species of Floridotarsonemus in having an unusually narrow gnathosomal capsule about 1.5 times longer than its width. (vs. gnathosomal capsule with subequal length and width in other species). The new species is most similar to F. scaber in having seta pl″ in the distal position to solenidion ω on tarsus II. The new species differs from F. scaber in having extended laterally apodeme 3, shorter setae c₂ 14–18 (vs. 22–24 in F. scaber), shorter setae e 7–9 and h 5–6 (vs. setae e and h 11 in length in F. scaber), and setae h more bluntly pointed than other dorsal setae (vs. tips of setae h not differ from other dorsal setae in F. scaber).

Floridotarsonemus humeophilus n. sp.

ZOOBANK: 18111E83-E675-4933-B1CC-5A4390B5BCE1

(Figs 1–5)

Female — Gnathosomal capsule (Figs 2A, B, 3A) subtriangular in shape, 1.5 times longer than wide, connected with idiosoma with membranous cuticle. Length of gnathosomal capsule 28 (28–30), width 18 (15–20). Palpcoxal setae (pp) 9 (9–12) present laterally. Dorsal gnathosomal setae (ch) 13 (12–14) smooth, simple. Palpi short 10 (9–10), with tiny setae (dGE) and round inconspicuous process on distal extremity. Ventral gnathosomal setae (m) 12 (10–14) smooth and pointed. Cheliceral stylets 8 (7) and their levers short. Pharynx medium, muscular, with thin walls, width of pharynx 5 (5–6) occupies 1/3 part of gnathosomal width (Fig. 3A).Idiosomal dorsum (Figs 1A, 3C, D). Prodorsal shield expanded laterally. Stigmata small, round, located partially under prodorsal shield; trachea long, thin and narrow, without sclerotized sacks. Bothridia present, trichobothria (sc₁) clearly elongated, pilose, almost completely covered by prodorsal shield. Alveolar pits v₂ located at the same distance from both bases of setae v₁ and sc₂. All tergites with regular tiny puncta and delicate striation near posterior margin. Each tergite with smooth posterior margins. All dorsal setae smooth; setae h weakly blunt-tipped, other setae pointed. Lengths of dorsal setae: v₁ 15 (16–21), sc₂ 26 (26–28), c₁ 14 (12–15), c₂ 16 (14–18), d 9 (9–11), e 7 (7–9), f 12 (11–13), h 6 (5–6). Distances between setae: v₁– v₁31 (32–33), v₂ – v₂ 41 (40–42), sc₂– sc₂ 51 (46–50), c₁– c₁78 (76–82), c₂– c₂ 104 (100–107), c₁– c₂ 31 (29–33), d–d 39 (36–41), e–e 70 (67–72), e–f 30 (25–31), f –f 17 (15–22), h–h 37 (33–38).

Idiosomal venter (Figs 1B, 3A, B). All ventral plates with tiny uniform puncta. Prosternal apodeme (appr) distally with small y-shaped bifurcation and nodule in middle part, not fused with sejugal apodeme (apsej). Apodemes 2 (ap2) not fused with prosternal apodeme (appr), with two nodules: one in the middle part, other at the end. Sejugal apodeme indistinct, continuous. All ventral setae smooth and pointed. Lateral ends of apodemes 3 (ap3) extended laterally, apodemes 3 with three nodules. Apodeme 4 (ap4) with nodules, anterior ends of apodemes not fused with poststernal apodeme (appo). Posterior ends of ap 4 reach base of setae 3b. Tegula 6 (5–7) long, 13 (13–15) wide, with slightly convace sides. Posterior sternal plate with angular sharp process between trochanter III and IV. Length of ventral setae: 1a 8 (8–9), 2a 13 (13–14), 3a 11 (11–13), 3b 12 (9–12), ps 8 (7–9). Width of tegula 13 (13–15), length of tegula 6 (5–7).

Legs (Figs 4A–E, 5A, B, 3A, B). Chaetotaxy (including unguinal setae u′, u″ on tibiotarsus I and u″ on tarsi II and III) of leg I: Fe4–Ge4–TiTa6(2ϕ) +10(1ω); leg II: Fe3–Ge3–Ti4–Ta7(1ω); leg III: FeGe1+3–Ti4–Ta6; legIV: FeGe1+1–TiTa1+1. Length of legs: I 47 (48–53), II 48 (45–46), III 43 (41–43), IV 28 (22–24). Leg I (Figs 4A, B). Femur with flange (Fig. 4B). Solenidion ω elongated, digitiform; solenidia ϕ1 and ϕ2 clublike and elongate; seta k 3 (3–4) baculiform, slightly shorter that solenidion ϕ1. Lengths of solenidia: ω 5 (5–6), ϕ1 5 (5), ϕ2 3 (2–3). Setae: l″, l′, and d of femur barbed and blunt-tipped; seta v″ pointed and barbed. Seta l′ of genu barbed and blunt-tipped, other setae pointed and barbed. Setae d, pv″ of tibiotarsus smooth and pointed, seta s spiniform, eupathidia (p′, p″, tc′, tc″) smooth and blunt-tipped, other setae pointed and barbed. Leg II (Figs 4C–E). Solenidion ω 6 (5–6) elongated, digitiform. Femur with distinct flange (Fig. 4E). Tibia with characteristic sharp process. (Fig. 4D). Seta d of femur smooth, stout, blunt-tipped; seta l′ blunt-tipped, stout, barbed; seta v″ pointed and barbed. All setae of genu barbed and pointed. Tibia setae v″, l′, and v′ pointed and barbed; seta d smooth and pointed. Tarsus setae tc′, tc″, pv′ pointed and barbed; seta pv″ pointed and smooth; seta pl″ spiniform and located distally from solenidion ω close to base of seta tc″; seta u′ smooth, spiniform, u″ very small, pointed and smooth. Leg III (Fig. 5A). Setae v′Fe of femorogenu smooth, blunt-tipped; seta v′Ge barbed and pointed; setae l″Ge and l′Ge smooth and pointed. All tibial setae weakly barbed and pointed. Tarsal setae tc′ and pv″ barbed and pointed; setae tc″, pv′, and u″ smooth and pointed; seta u′ smooth, blunt, stout. Leg IV. (Fig. 5B). All setae smooth and pointed; measurements: v′Fe 6 (6–8), v′Ge 7 (8–10), v′Ti 11 (11–13), tc″ 42 (43–45).

Males and juvenile stage are unknown.

Type material — Female holotype, Slide ZISP T-Tar-003, Krasnodar Krai, vicinity of the city of Krasnodar, winter wheat field, extracted from soil, 6 April 2022, coll. A.A. Goncharov. Paratypes: 8 females, same data.

Type deposition — The holotype and one paratype are deposited in ZISP (Zoological Institute of Russian Academy of Sciense, St. Petersburg, Russia); other paratypes are deposited in the collection of the TSUMZ (Tyumen State University Museum of Zoology, Tyumen, Russia).

Etymology — The name of the species is a combination of two words, Latin humus meaning soil and Greek φίλος meaning love and refers to the soil habitat in contrast to plant habitats of other Floridotarsonemus species.

Keys to the world species of Floridotarsonemus (based on females)

1. Poststernal apodeme bifurcated anteriorly, tegula with posterior margin rounded and often extended beyond the margin of trochanter IV
...... 2

— Poststernal apodeme blunt anteriorly, tegula with posterior margin truncated confined within the margin of trochanter IV
...... F. evodiae

2. Idiosomal setae d and f thin, pointed
...... 3

— Idiosomal setae d and f needle-like, blunt-tipped
...... F. kukri

3. Gnathosomal capsule subequally as wide as long
...... 4

— Gnathosomal capsule narrow, ratio length/width 1.5
...... F. humeophilus n. sp.

4. Seta pl″ of tarsus II located clearly anteriad base of solenidion ω
...... 5

— Seta pl″ of tarsus II located at the same level as solenidion ω
...... F. edule

5. Seta pl″ of tarsus II distinctly shorter than solenidion ω and located much closer to solenidion than to seta tc″
...... F. kanthali

— Seta pl″ of tarsus II subequal in length with solenidion ω and located near the base of seta tc″
...... F. scaber

Discussion

Floridotaronemus humeophilus n. sp. is the first species among the genus Floridotaronemus, which was found in soil (meadow-chernozem). All previously described species of this genus were found only on various plants. A narrow gnathosomal capsule (length greater than width) is an uncharacteristic feature for the genus Floridotarsonemus, but is often found in the genus Tarsonemus.

The authors who described the species of the genus Floridotaronemus did not mention possible damage to the plants caused by the mites. A study of the fauna of the tribe Tarsonemini of West Bengal, where the genus Floridotarsonemus was found on different plants, did not show strict specificity to the host plants and concluded that the mites propably feed on epiphytic fungi (Mondal et al. 2023). Unfortunately, at the moment there are no studies considering the food preferences of the genus Floridotarsonemus. If Floridotaronemus humeophilus prefers fungi for nutrition, then probably this can explain its presence in the soil, an environment with a large abundance and variety of fungi.

Acknowledgements

Dr. Jacob Wickham kindly improved the English of an advanced draft of the manuscript. This study was funded by the Russian Science Foundation (Project No 22–76–10027).

References

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