Ermilov, Sergey G. ¹ ; Kontschán, Jenő ² ; Salavatulin, Vladimir M. ³ and Khaustov, Vladimir A. ⁴

¹✉ University of Tyumen, X-BIO Institute, Tyumen, Russia.
²Plant Protection Institute, HUN-REN Centre for Agricultural Research, Budapest, Hungary & Széchenyi István University, Department of Plant Sciences, Albert Kázmér Faculty of Mosonmagyaróvár, Mosonmagyaróvár, Hungary.
³University of Tyumen, X-BIO Institute, Tyumen, Russia & Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, Russia & Joint Russian-Vietnamese Tropical Research and Technological Centre, Southern Branch, Ho Chi Minh City, Vietnam.
⁴University of Tyumen, X-BIO Institute, Tyumen, Russia & Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, Russia & Joint Russian-Vietnamese Tropical Research and Technological Centre, Southern Branch, Ho Chi Minh City, Vietnam.

2025 - Volume: 65 Issue: 4 pages: 1068-1081

ZooBank LSID: 0887E47F-74ED-47FC-995D-F31312F0B367

Original research

Keywords

Abstract

Introduction

The oribatid mite genus Dolicheremaeus (Acari, Oribatida, Otocepheidae) was proposed by Jacot (1938), with Dolicheremaeus rubripedes Jacot, 1938 as type species. The genus comprises 183 species and nine subspecies which are distributed in the Tropical and Subtropical areas collectively (Subías 2022, unpublished version 2024; Ermilov, personal data). The main distinguishing generic traits can be found in Aoki (1967), Corpuz-Raros (2000), Subías and Shtanchaeva (2023). Representatives of Dolicheremaeus mainly inhabit forest soil-litter and various ground substrates (e.g., Aoki 1967; Corpuz-Raros and Ermilov, 2019, 2020).

Among the oribatid mite materials collected from the Kon Chu Rang Nature Reserve (central Vietnam), two new species of Dolicheremaeus are found. The primary goal of the paper is to describe these two new species.

According to the catalogue of Corpuz-Raros and Ermilov (2020), 25 species of Dolicheremaeus have been registered in Vietnam. Of them, D. auritus (Aoki, 1965) (in 1965b) and D. ornatus (Balogh and Mahunka, 1967) are rightly considered representatives of the genus Megalotocepheus Aoki, 1965 (in 1965a) (Subías 2022, unpublished version 2024) due the morphology of the pedotectum II (its posterolateral part distinctly protruding in Megalotocepheus versus not protruding in Dolicheremaeus). Additionally, Ha and Vu (2020) recorded D. montanus Krivolutsky, 1971, and Ermilov et al. (2025) described D. leonilae Ermilov, Salavatulin and Khaustov, 2025 from Vietnam. Dolicheremaeus montanus is distributed in the southern Palaearctic region. Its description is brief, and the morphology is unclear in detail (Krivolutsky 1971). Therefore, a correct identification of this species is difficult, and the claim of its occurrence in the Vietnamese fauna (Ha and Vu 2020) needs to be confirmed.

Ermilov and Anichkin (2014b) presented an identification key to the 13 Vietnamese species of Dolicheremaeus. However, since then, several new species have been described, many new findings have been recorded, and some taxonomic combinations have been made. Therefore, the secondary goal of the paper is to provide a new identification key to the known species of Dolicheremaeus from Vietnam.

Methods

Observation and documentation — For measurement and illustration, specimens were mounted in lactic acid on temporary cavity slides. All body measurements are presented in micrometers (µm). Body length was measured in lateral view, from the tip of the rostrum to the posterior edge of the notogaster. Body width refers to the maximum width of the notogaster in dorsal view. Body setae were measured in lateral aspect. Formulas for leg setation are given in parentheses according to the sequence trochanter-femur-genu-tibia-tarsus (famulus of tarsus I included). Formulas for leg solenidia are given in square brackets, according to the sequence genu-tibia-tarsus. Paired structures are described in the singular, unless otherwise noted. Drawings were made with a camera lucida using a Leica DM 2500 light microscope. Images were obtained with an AxioCam ICc3 camera using a Carl Zeiss transmission light microscope Axio Lab.A1.

Terminology — Morphological terminology mostly follows that of Grandjean (see references in Travé and Vachon 1975). Fundamentals of leg setation were reviewed by Norton (1977).

Abbreviations — Prodorsum: cos = costula; ro, le, in, bs, ex = rostral, lamellar, interlamellar, bothridial, and exobothridial setae, respectively; cpl = lateral prodorsal condyle. Notogaster: cnm, cnl = medial and lateral notogastral condyles, respectively; c, la, lm, lp, h₁–h₃, p₁–p₃ = setae; ia, im, ip, ih, ips = lyrifissures; gla = opisthonotal gland opening. Gnathosoma: a, m, h = subcapitular setae; d, l, sup, inf, cm, ul, su, vt, lt = palp setae; ω = palp solenidion; cha, chb = cheliceral setae; Tg = Trägårdh's organ. Epimeral and lateral podosomal regions: 1a, 1b, 1c, 2a, 3a, 3b, 3c, 4a, 4b, 4c = epimeral setae; PdI, PdII = pedotecta I, II, respectively; dis = discidium. Anogenital region: r = ridge; g, ag, an, ad = genital, aggenital, anal, and adanal setae, respectively; iag, iad = aggenital and adanal lyrifissures, respectively; po = preanal organ. Legs: ω, φ, σ = solenidia; e = famulus; d, l, v, bv, ev, ft, tc, it, p, u, a, s, pv = setae; pa = porose area.

Descriptions

Dolicheremaeus gialaiensis n. sp.

ZOOBANK: 8F1AF3AF-AD15-4772-B767-CCB5C77179E2

(Figures 1, 3a, 4a–c, h–j, 5)

Type material — Holotype (female) and seven paratypes (six males and one female): Vietnam, Gia Lai Province, K'Bang District, Son Lang Commune, Kon Chu Rang Nature Reserve, 14°28′06.43″ N, 108°33′59.48″ E, 1020 m a.s.l., litter in forest, 13 March 2025, collected by V.A. Khaustov and V.M. Salavatulin.

The holotype is deposited in the collection of the Senckenberg Museum of Natural History, Görlitz, Germany; two paratypes are deposited in the collection of the University of Tyumen, Museum of Zoology, Tyumen, Russia; five paratypes are in the personal collection of the first author. All specimens are preserved in 70% solution of ethanol with a drop of glycerol.

Diagnosis — Body length 585–750. Notogaster and anogenital region with small, dense, conical tubercles. Genital plate with longitudinal ridges. Interlamellar seta rod-like, sparsely barbed, longer than rostral and lamellar setae. Bothridial seta clavate, with slightly developed head having one distal tooth. Medial prodorsal and notogastral condyles absent. Notogastral setae c, la, lm, lp, h₂ rod-like, other setae longer, subflagellate, all sparsely barbed. Adanal seta ad₂ longer than ad₁ and ad₃, seta ad₃ shifted to margin of ventral plate. Adanal lyrifissure oblique, close to anal plate. Setae u′ and u″ setiform (on tarsus I) and thorn-like (on tarsi II–IV).

Description — Measurements – Body length 750 (holotype), 585–615 (male paratypes), 720 (female paratype). Body width 375 (holotype), 270–300 (male paratypes), 360 (female paratype). Body ratio (length/width) 2.0–2.1.

Integument (Figures 1a, b, 3a, 4c) – Body color light brown to yellowish, but legs and genital plates brown. Body surface densely microgranulate. Additionally, notogaster, anogenital region, and intercostular region (partially) of prodorsum with small, dense, conical tubercles having distinct point (Fig. 4c), and epimeral region, podosomal region (between bothridium and acetabula I–III), anal plate, mediobasal part (partially) of prodorsum, and lateral part of notogaster with simple tubercles. Genital plate with dense, longitudinal ridges.

Prodorsum (Figures 1a, 3a, 4a, b) – Rostrum broadly rounded. Costula long, protruding anterior to insertion of lamellar seta. Tutorial carina absent. Rostral (79–90) and lamellar (82–94) setae setiform, barbed. Interlamellar seta (105–131) rod-like, sparsely barbed. Bothridial seta (90–120) clavate, with long stalk and short, slightly developed head having one distal tooth. Exobothridial seta (34–45) setiform, roughened. One pair of lateral prodorsal condyles tubercle-like. Medial prodorsal condyles absent.

Notogaster (Figures 1a, b, 3a) – One pair of lateral notogastral condyles triangular. Medial notogastral condyles absent. Ten pairs of notogastral setae. Setae c, lm (82–101), la, lp, h₂ (90–112) rod-like, sparsely barbed. Setae h₃ (131–142), h₁, p₁–p₃ (180–202) subflagellate, sparsely barbed. Opisthonotal gland opening and all lyrifissures distinct, ia posterolateral to c, gla and im close to each other, posterolateral to lm, ip between p₂ and p₃, ips between p₃ and h₃, ih anterior to h₃.

Gnathosoma (Figures 4h–j) – Subcapitulum size 150–154 × 101–109. Subcapitular seta h (45–49) setiform, barbed, setae a (26–30) and m (41–45) setiform, roughened. Palp length 90–94. Palp setal formula 0-2-1-3-8(+ω). Postpalpal seta (7–9) spiniform, smooth. Chelicera length 150–154. Cheliceral seta cha (49–52) setiform, barbed, seta chb (19–22) thinner, setiform, roughened.

Epimeral and lateral podosomal regions (Figures 1b, 3a) – Epimeral setal formula 3-1-3-3. Setae 1a, 2a, 3a, 4b (26–34), 4c (34–41) setiform, slightly barbed, 1b, 1c, 3b, 3c, 4a (56–60) setiform, barbed. Pedotectum I as large lamina, pedotectum II as small lamina.

Anogenital region (Figures 1b, 3a) – Anogenital setal formula 4-1-2-3. Genital (26–34), aggenital (45–56), anal (an₁ 49–56; an₂ 56–67), and adanal (ad₁ 60–75; ad₂ 97–120; ad₃ 82–90) setae setiform, barbed. Adanal seta ad₃ distant from anal plate, shifted to margin of ventral plate. Adanal lyrifissure oblique, close to anal plate.

Legs (Figures 5a–d) – Claw of each leg strong, slightly barbed on dorsal side. Dorsal side of tarsi I, II with one small tooth. Dorsoparaxial porose area on femora I–IV and on trochanters III, IV well visible. Formulas of leg setation and solenidia: I (1-4-3-4-16) [1-2-2], II (1-4-3-3-15) [1-1-2], III (2-3-1-2-15) [1-1-0], IV (1-2-2-2-12) [0-1-0]. Homology of setae and solenidia indicated in Table 1. Setae u′ and u″ setiform (on tarsus I) and thorn-like (on tarsi II–IV). Setae pv″ of tarsus IV dilated mediodistally, ciliate.

Remarks — Dolicheremaeus gialaiensis n. sp. differs from all species of the genus in the presence of unusual sculpturing (small, dense, conical tubercles having distinct point) of the prodorsum, notogaster, and anogenital region.

Etymology — The species name gialaiensis refers to the province of origin, Gia Lai.

Dolicheremaeus kbangensis n. sp.

ZOOBANK: E290328C-E9B6-4AFE-9031-34DACBE05EFF

(Figures 2, 3b, 4d–g)

Type material — Holotype (male) and three paratypes (two males and one female): Vietnam, Gia Lai Province, K'Bang District, Son Lang Commune, Kon Chu Rang Nature Reserve, 14°29′35.71″ N, 108°32′39.11″ E, 1044 m a.s.l., litter in forest, 14 March 2025, collected by V.A. Khaustov and V.M. Salavatulin.

The holotype is deposited in the collection of the Senckenberg Museum of Natural History, Görlitz, Germany; three paratypes are deposited in the collection of the University of Tyumen, Museum of Zoology, Tyumen, Russia. All specimens are preserved in 70% solution of ethanol with a drop of glycerol.

Diagnosis — Body length 585–675. Notogaster and anogenital region with narrowly elongate tubercles. Genital plate with longitudinal ridges. Interlamellar seta rod-like, sparsely barbed, longer than rostral and lamellar setae. Bothridial seta lanceolate, with slightly developed, roughened head. Medial prodorsal condyles absent. Medial notogastral condyles small, located close to lateral notogastral condyles. All notogastral setae comparatively long, nearly rod-like, with short attenuate tip, sparsely barbed. Adanal seta ad₃ shifted to margin of ventral plate. Adanal lyrifissure parallel and close to anal plate. Setae u′ and u″ setiform (on tarsus I) and thorn-like (on tarsi II–IV).

Description — Measurements – Body length 645 (holotype), 585, 600 (male paratypes), 675 (female paratype). Body width 315 (holotype), 285 (male paratypes), 375 (female paratype). Body ratio (length/width) 1.8–2.1.

Integument (Figures 2a, b, 3b, 4f, g) – Body color light brown to yellowish, but legs and genital plates brown. Body surface densely microgranulate. Additionally, notogaster with narrowly elongate tubercles (Figs 4f, g) creating illusion of short ridges in dorsal aspect, podosomal region (between bothridium and acetabula I–III), ventral side, anal plate, medioanterior part of prodorsum, and lateral part of notogaster with simple tubercles. Genital plate with dense, longitudinal ridges. Ventral side of pedotectum II with some foveolae.

Prodorsum (Figures 2a, 3b, 4d, e) – Rostrum broadly rounded. Costula long, protruding anterior to insertion of lamellar seta. Tutorial carina absent. Rostral (75–82) and lamellar (90–94) setae setiform, barbed. Interlamellar seta (131–161) nearly rod-like, sparsely barbed. Bothridial seta (131–139) lanceolate, with long stalk and short, slightly developed, roughened head. Exobothridial seta (34–41) setiform, roughened. One pair of lateral prodorsal condyles tubercle-like. Medial prodorsal condyles absent.

Notogaster (Figures 2b, 3b) – One pair of lateral notogastral condyles tubercle-like. One pair of medial notogastral condyles small, tubercle-like, located close to lateral condyles. Ten pairs of notogastral setae. Setae c, la, lm (116–139), lp, h₁–h₃, p₁–p₃ (131–157) nearly rod-like, with short attenuate tip, sparsely barbed. Opisthonotal gland opening and all lyrifissures distinct, ia posterolateral to c, gla and im close to each other, posterolateral to lm, ip between p₂ and p₃, ips between p₃ and h₃, ih anterior to h₃.

Gnathosoma – Generally, similar to D. gialaiensis n. sp. except sizes. Subcapitulum size 131–135 × 82–90. Length of subcapitular seta a 26, m and h 56. Palp length 79–86. Length of postpalpal seta 7. Chelicera length 131–135. Length of cheliceral seta cha 41–49, chb 19.

Epimeral and lateral podosomal regions (Figures 2b, 3b) – Epimeral setal formula 3-1-3-3. Setae 1a, 2a, 3a, 4b (22–37), 4c (34–41) setiform, roughened, 1b, 3b, 3c (52–67), 1c, 4a (67–79) setiform, barbed. Pedotectum I as large lamina, pedotectum II as medium-sized lamina.

Anogenital region (Figures 2a, b, 3b) – Anogenital setal formula 4-1-2-3. Morphology of genital setae (22–26) variable, spiniform, nearly smooth or setiform, slightly barbed. Aggenital (41–49), anal (an₁ 49–53; an₂ 53–67), and adanal (67–79) setae setiform, barbed. Adanal seta ad₃ distant from anal plate, shifted to margin of ventral plate. Adanal lyrifissure parallel and close to anal plate.

Legs – Generally, similar to D. gialaiensis n. sp., but dorsal side of tarsi I, II without one small tooth.

Remarks — Dolicheremaeus kbangensis n. sp. is similar to D. baloghi Aoki, 1967 and D. lineolatus Balogh and Mahunka, 1967 in the presence of small medial notogastral condyles located close to lateral notogastral condyles, and in the absence of the medial prodorsal condyles. However, the new species differs from both species in the presence of the dense narrowly elongate tubercles on the notogaster (versus tubercles absent), slightly developed, lanceolate bothridial seta (versus well developed, clavate-fusiform), and longer notogastral setae (lm longer than distance lm–h₂ versus lm not longer than distance lm–h₂). Additionally, in D. baloghi, genital plate without longitudinal ridges (versus with ridges), and anal plate with oblique sclerotized line (versus without line); in D. lineolatus, surface of notogaster foveolate (versus foveolae absent).

Etymology — The species name kbangensis refers to the district of origin, K′Bang.

Key to Dolicheremaeus from Vietnam

The morphological data of Aoki (2006) on D. orientalis are not included in the key because they differ from those in the original description in important characters (Aoki 1965b). For example, the supplementary description showed the absence (versus presence in Aoki 1965b) of the medial notogastral condyles as well as bothridial seta with well-developed head (versus nearly bacilliform in Aoki 1965b).

The designations of some notogastral setae (e.g. lp, h₁–h₃, p₁–p₃) are mixed up in some original papers, therefore, they are presented in the key according to the modern interpretation (see present figures).

Dolicheremaeus montanus is excluded from the key due its poor description (Krivolutsky 1971).

1. Medial prodorsal condyles absent
...... 2

— One pair of medial prodorsal condyles present
...... 8

2. Medial notogastral condyles absent
...... 3

— One pair of small medial notogastral condyles present, located close to lateral notogastral condyles
...... 6

3. Notogaster with conical tubercles. Notogastral setae h₁, h₃, p₁–p₃ distinctly longer than other notogastral setae, subflagellate. Bothridial seta clavate, with one tooth. Adanal lyrifissure oblique to anal plate. Body length 585–750
...... Dolicheremaeus gialaiensis n. sp. Distribution: Vietnam

— Notogaster without conical tubercles. All notogastral setae slightly differs in length, rod-like. Bothridial seta lanceolate, without tooth. Adanal lyrifissure parallel to anal plate
...... 4

4. Anterior part of notogaster with medial depression. Anal plate with longitudinal sclerotized line. Body length 879–915
...... Dolicheremaeus bartkei Rajski and Szudrowicz, 1974. Distribution: Vietnam

— Anterior part of notogaster without medial depression. Anal plate without longitudinal sclerotized line
...... 5

5. Genital plate with longitudinal ridges. Notogastral seta lp inserted nearly between lm and h₃. Longitudinal ridge present lateral to genital plate. Body length 784
...... Dolicheremaeus aokii (Balogh & Mahunka, 1967). Distribution: Vietnam

— Genital plate without longitudinal ridges. Notogastral seta lp inserted nearly between lm and h₂. Longitudinal ridge absent lateral to genital plate. Body length 569–675
...... Dolicheremaeus oginoi (Aoki, 1965) (in 1965b). Distribution: Oriental region

6. Notogaster with narrowly elongate tubercles. Notogastral seta lm longer than distance lm–h₂. Bothridial seta lanceolate, with slightly developed head. Body length 585–675
...... Dolicheremaeus kbangensis n. sp. Distribution: Vietnam

— Notogaster without narrowly elongate tubercles. Notogastral seta lm not longer than distance lm–h₂. Bothridial seta clavate or fusiform, with well-developed head
...... 7

7. Notogaster foveolate. Genital plate with longitudinal ridges. Notogastral seta lp equally distant from lm and h₂. Anal plate without oblique sclerotized line. Body length 686
...... Dolicheremaeus lineolatus Balogh and Mahunka, 1967. Distribution: Vietnam

— Notogaster not foveolate. Genital plate without longitudinal ridges. Notogastral seta lp located closer to lm than to h₂. Anal plate with oblique sclerotized line. Body length 710–785
...... Dolicheremaeus baloghi Aoki, 1967. Distribution: eastern Palaearctic and Oriental regions

8. Medial notogastral condyles represented by five to seven, slightly developed parts. Body length 450–480
...... Dolicheremaeus leonilae Ermilov, Salavatulin and Khaustov, 2025. Distribution: Vietnam

— Medial notogastral condyles absent or represented by one pair
...... 9

9. Medial notogastral condyles absent
...... 10

— One pair of medial notogastral condyles present
...... 11

10. Bothridial seta clavate. Notogastral seta lp located closer to lm than to h₂. Exobothridial seta longer than diameter of bothridium. Body length 550
...... Dolicheremaeus bruneiensis Aoki, 1967 (see also Mahunka 1991). Distribution: Oriental region

— Bothridial seta lanceolate. Notogastral seta lp equally distant from lm and h₂. Exobothridial seta shorter than diameter of bothridium. Body length 900–950
...... Dolicheremaeus junichiaokii Subías, 2010 (=Dolicheremaeus magnus Aoki, 2006). Distribution: Japan, Oriental region

11. Notogastral setae of medioposterior part of notogaster distinctly longer than other notogastral setae, subflagellate
...... 12

— All notogastral setae slightly differs in length, nearly rod-like
...... 13

12. Medial notogastral condyles located close to each other and distant from lateral notogastral condyles. All adanal setae slightly differ in length. Body length 514–614
...... Dolicheremaeus donacunarensis Ermilov and Anichkin, 2014 (in 2014b). Distribution: Vietnam

— Medial notogastral condyles equally distant from each other and lateral notogastral condyles. Adanal seta ad₂ distinctly longer than ad₁ and ad₃. Body length 837
...... Dolicheremaeus capillatus capillatus (Balogh, 1959). Distribution: Afrotropical region, Vietnam

13. All notogastral setae short (lm about 1/3 of distance lm–h₂ or shorter)
...... 14

— All notogastral setae medium-sized or long (lm about 1/2 of distance lm–h₂ or longer)
...... 15

14. Interlamellar seta short, similar to notogastral setae in length, erect. Bothridial seta clavate, with short, nearly rounded head. Adanal seta ad₃ located in paraanal position. Longitudinal ridge present lateral to genital plate. Leg setae u′ and u″ of all tarsi setiform. Body length 381–564
...... Dolicheremaeus dwalteri Ermilov and Anichkin, 2014 (in 2014b). Distribution: Vietnam

— Interlamellar seta long, distinctly longer than notogastral setae, bent in mediobasal part. Bothridial seta asymmetrically lanceolate, with narrowly elongate head. Adanal seta ad₃ located in preanal position. Longitudinal ridge absent lateral to genital plate. Leg setae u′ and u″ of all tarsi thorn-like. Body length 518–534
...... Dolicheremaeus variolatus Mahunka, 1989. Distribution: Oriental region

15. Bothridial seta pectinate, with four to six branches unilaterally. Body length 614–863
...... Dolicheremaeus insolitus Ermilov and Anichkin, 2014 (in 2014a). Distribution: Vietnam

— Bothridial seta not pectinate
...... 16

16. Bothridial seta with distinctly elongate swollen in middle. Notogaster with 11 or 12 pairs of setae. Body length 775–1003
...... Dolicheremaeus mutabilis Aoki, 1967. Distribution: New Guinea, Vietnam

— Bothridial seta without swollen in middle. Notogaster with 10 pairs of setae
...... 17

17. Bothridial seta nearly bacilliform, without distinctly developed head
...... 18

— Bothridial seta with distinctly developed head
...... 19

18. Interlamellar seta medium-sized, shorter than bothridial seta. Dorsal notogastral setae medium-sized (lm about 2/3 of distance lm–h₂). Lateral notogastral condyle covers distal part of lateral prodorsal condyle. Aggenital seta medium-sized. Leg tarsi I, II without dorsal teeth. Body length 1045–1211
...... Dolicheremaeus contactus Ermilov and Anichkin, 2013. Distribution: Vietnam

— Interlamellar seta long, longer than bothridial seta. Dorsal notogastral setae long (lm equal to distance lm–h₂). Lateral prodorsal and notogastral condyles distinctly separated. Aggenital seta short. Leg tarsi I, II with dorsal teeth. Body length 852–1015
...... Dolicheremaeus orientalis (Aoki, 1965) (in 1965b). Distribution: Oriental region, Japan

19. Dorsal notogastral setae long (lm equal to distance lm–h₂)
...... 20

— Dorsal notogastral setae medium-sized (lm about 1/2 or 2/3 of distance lm–h₂)
...... 22

20. Adanal seta ad₃ not shifted to margin of ventral plate (distance ad₃–ad₃ equal to ad₂–ad₂). Adanal lyrifissure distant from anal plate. Genital plate lineolate. Body length 770
...... Dolicheremaeus hammerae Corpuz-Raros, 2000 (=Dolicheremaeus lineolatus Hammer, 1981; in 1981a). Distribution: Oriental region

— Adanal seta ad₃ shifted to margin of ventral plate (distance ad₃–ad₃ distinctly larger than ad₂–ad₂). Adanal lyrifissure close to anal plate. Genital plate not lineolate
...... 21

21. Medial notogastral condyles located closer to lateral notogastral condyles than to each other. Notogastral seta lp located closer to lm than to h₂. Body length 759
...... Dolicheremaeus inaequalis Balogh and Mahunka, 1967. Distribution: Vietnam

— Medial notogastral condyles equally distant form each other and lateral notogastral condyles. Notogastral seta lp equally distant from lm and h₂. Body length 445–518
...... Dolicheremaeus sabahnus Mahunka, 1988. Distribution: Oriental region

22. Adanal seta ad₃ located in preanal position
...... 23

— Adanal seta ad₃ located in paraanal position
...... 24

23. Genital plate with longitudinal ridges. Leg setae u′ and u″ of all tarsi setiform. Notogaster not foveolate. Body length 479–660
...... Dolicheremaeus philippinensis Aoki, 1967 (see also Corpuz-Raros 2000). Distribution: Oriental region

— Genital plate without longitudinal ridges. Leg setae u′ and u″ setiform (tarsi I, II) and thorn-like (tarsi III, IV). Notogaster foveolate. Body length 763–780
...... Dolicheremaeus bugiamapensis Ermilov, Anichkin and Wu, 2012. Distribution: Vietnam

24. Genital plate with longitudinal ridges. Leg setae u′ and u″ of all tarsi setiform. Body length 536–560
...... Dolicheremaeus damaeoides (Berlese, 1913) (=Tetracondyla pallida Newell, 1956) (see also Balogh 1968; Mahunka & Mahunka-Papp 1995). Distribution: Tropical region

— Genital plate without longitudinal ridges. Leg setae u′ and u″ setiform (tarsi I, II) and thorn-like (tarsi III, IV)
...... 25

25. Rostrum nasiform, protruding medially. Notogastral seta lp located closer to lm than to h₂. Adanal lyrifissure close to anal plate. Body length 550
...... Dolicheremaeus nasalis Hammer, 1981 (in 1981b). Distribution: Oriental region

— Rostrum rounded, not protruding. Notogastral seta lp equally distant from lm and h₂. Adanal lyrifissure distant from anal plate. Body length 972
...... Dolicheremaeus pustulatus Mahunka, 1989. Distribution: Oriental region

Acknowledgements

We thank Dr. Julia Baumann (University of Graz, Graz, Austria) and two anonymous reviewers for their valuable comments and the staff of the Kon Chu Rang Nature Reserve for their support during fieldwork. The work was performed within the framework of the Joint Russian-Vietnamese Biological Expedition, financially supported by the Russian Academy of Sciences. The collection of materials was conducted under the Agreement on the Scientific Cooperation between the Joint Russian-Vietnamese Tropical Research and Technological Center and the Kon Chu Rang Nature Reserve.

References

1. Aoki J. 1965a. A preliminary revision of the family Otocepheidae (Acari, Cryptostigmata). I. Subfamily Otocepheinae. Bul. Nat. Mus. Nat. Sci., 8: 259-341.
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