The oribatid mite genus Hardybodes (Acari, Oribatida, Carabodidae) was proposed by Balogh, 1970 with Hardybodes mirabilis Balogh, 1970 as type species. It comprises three species (Balogh 1970; Mahunka 1995), which are distributed in the Oriental and Australian regions: H. flabellatus Mahunka, 1995 and H. penicillatus Mahunka, 1995 were described from soil of tropical forest on Borneo (Mahunka 1995); H. mirabilis Balogh, 1970 from litter of small forest in New Guinea and also recorded in different plant associations in the Philippines (Corpuz-Raros 1979) and in litter of tropical forests on Borneo (Mahunka 1987). Subías (2004, online version 2017) considers the genus Carabodella Mahunka, 1986(b) as the junior synonym of Hardybodes, including its type species Carabodella calcarata Mahunka, 1986(b) in the latter. However, we support independence of Carabodella after explanations of Fernandez et al. (2015).

In the course of taxonomic study of new materials of carabodid mites from the collection of the Museum of Natural History (University of the Philippines Los Baños), we found a new species of Hardybodes. It is the fourth representative of the genus, and the species is second only to H. mirabilis which was recorded earlier (e.g. Corpuz-Raros 1979) for the Philippine fauna.

This paper aims to describe and illustrate the new species, update generic diagnosis and give an identification key to known species of the genus Hardybodes.

Material examined — Holotype (male) and one paratype (male): Philippines, Luzon Island, boundary between Laguna and Quezon Provinces, University of the Philippines Land Grant, nest in soil of unknown species of ants (Formicidae) (the nest is located by following major ant trails), extracted with Berlese funnel, 23.I.2016 (collected by R. Garcia, J. Naredo and H. Klompen).

Methods — Specimens were mounted in lactic acid on temporary cavity slides for measurement and illustration. Body length was measured in lateral view, from the tip of the rostrum to the posterior edge of the ventral plate. Notogastral width refers to the maximum width of notogaster. Lengths of body setae were measured in lateral aspect. All body measurements are presented in micrometers. Formulas for leg setation are given in parentheses according to the sequence trochanter–femur–genu–tibia–tarsus (famulus included). Formulas for leg solenidia are given in square brackets according to the sequence genu–tibia–tarsus. Drawings were made with a camera lucida using a Leica transmission light microscope “Leica DM 2500”. Morphological terminology used in this paper follows that of F. Grandjean: see Travé and Vachon (1975) for references, Norton (1977) for leg setal nomenclature, and Norton and Behan–Pelletier (2009), for overview.

The following abbreviations are used on the figures: lam – lamella; ro, le, in, bs – rostral, lamellar, interlamellar and bothridial setae, respectively; tu – tutorium; con – concavity; c, da, dm, dp, la, lm, lp, h, p – notogastral setae; ia, im, ip, ih, ips – notogastral lyrifissures; gla – opisthonotal gland opening; csb – circumgastric sigillar band; h, m, a – subcapitular setae; v, l, d, cm, ul, sul, vt, lt – palp setae; cha, chb – cheliceral setae; Tg – Trägårdh’s organ; Pd I, Pd II – pedotecta I and II, dis – discidium; 1a, 1b, 1c, 2a, 3a, 3b, 3c, 4a, 4b, 4c – epimeral setae; g, ag, an, ad – genital, aggenital, anal and adanal setae, respectively; iad – adanal lyrifissure; p.o. – preanal organ; ω, σ, ϕ – solenidia; ε – leg famulus; v, ev, bv, l, d, ft, tc, it, p, u, a, s, pv – leg setae.

The following collections are used: SMNH – Senckenberg Museum of Natural History, Görlitz, Germany; TSUMZ – Tyumen State University Museum of Zoology, Tyumen, Russia.

Type species: Hardybodes mirabilis Balogh, 1970, p. 298

Updated generic diagnosis (based on Balogh 1970; Mahunka 1986a; Fernandez et al. 2013, 2015)

Adult — Carabodidae (e.g. Mahunka 1986a; Norton and Behan-Pelletier 2009). Body elongated, ratio (length/width): ≈ 2.0. Body surface microgranulate, notogaster mostly tuberculate. Rostral margin rounded. Lamellae broad, well separated, located dorsolaterally. Translamella and interlamellar processes absent. Tutorium lineate or triangular distally. Rostral, lamellar and interlamellar setae short, setiform or slightly phylliform (exception: le bifurcate), ro inserted on prodorsal surface, near to the rostrum, in inserted on lamellae. Bothridial setae spathulate or thickened. Dorsosejugal region without deep concavities. Notogaster without large apophyses and ridges. Fifteen pairs of short, setiform or phylliform notogastral setae widely spaced, posterior part of notogaster with four pairs of setae (h ₃, p ₁–p ₃). Humeral shoulders slightly developed, with two pairs of notogastral setae (c ₂, c ₃). Epimeral setal formula 3–1–3–3; setae minute, 1a inserted clearly anterior to 1b. Four pairs of simple or slightly phylliform genital setae. Adanal setae ad ₁ and ad ₂ postanal, ad ₃ preanal. Leg setae u on tarsi I setiform, II–IV thorn-like.

Juvenile instars — Not known.

ZOOBANK: E41DB0ED-5505-4971-9FC9-702D6C26463C

Diagnosis — Body size: 281 × 135–143. Rostral, lamellar and interlamellar setae short, narrowly phylliform, smooth. Bothridial setae of medium size, spathulate. Notogaster with hump-like median part and anterolateral and posterolateral concavities. Notogastral setae short, narrowly phylliform, smooth, setae da, dm, dp, lm, lp, h ₁, h ₂ inserted in a longitudinal row dorsomedially. Subcapitular setae h shorter than a and m. Epimeral, genital, aggenital and anal setae short, setiform, smooth. Adanal setae slightly phylliform, smooth. Leg tarsi IV with 11 setae (pv” absent), setae l” of genua I, II dilated distally.

Description — Measurements – Medium size. Body length: 281 (holotype, male), 281 (one paratype, male); notogaster width: 143 (holotype), 135 (paratype). Integument (Figs 1A, 2B, 4B) – Body brown. Body (including genital and anal plates, subcapitular mentum and genae) and legs densely granulate (diameter of granules up to 1), notogaster and some leg segments partially tuberculate (diameter of tubercles up to 8). Prodorsum (Figs 1A–B, 2A, 3A) — Rostrum broadly rounded. Lamellae slightly shorter than prodorsum, broadly triangular distally. Rostral (10), lamellar (10) and interlamellar (10–12) setae narrowly phylliform, smooth. Bothridial setae (36–41) with short stalk and longer, spathulate, barbed head. Exobothridial setae and their alveoli absent. Tutoria with triangular tip. Anterolateral parts of prodorsum with pair of concavities.

Notogaster (Figs 1A–B, 2A–B, 3B) — Median part elongate, hump-like. Anterolateral and posterolateral parts with one large concavity. Humeral shoulders indistinct in dorsal view. Fifteen pairs of notogastral setae short (4–6), narrowly phylliform, smooth; of these, seven pairs (da, dm, dp, lm, lp, h ₁, h ₂) inserted in longitudinal row dorsomedially, c ₁ and da located close to each other. Lyrifissures, opisthonotal gland openings and circumgastric sigilla band well visible.

Gnathosoma (Figs 3C–E) — Subcapitulum longer than wide (57–61 × 49–53). Subcapitular setae (a, m, 6–8; h, 4–6) setiform, smooth. Adoral setae and their alveoli absent. Palps (32–36) with setation 0–2–1–3–8(+ω), acm absent. Solenidia (1/2 length of palptarsi) thickened, blunt-ended, pressed to the palptarsal surface. Postpalpal setae (2) spiniform, smooth. Chelicerae (57–65) with two setiform, barbed setae, cha (16–18) longer than chb (10–12). Trägårdh’s organ tapered.

Epimeral and lateral podosomal regions (Figs 1B, 2A) — Epimeral setal formula 3–1–3–3. All setae short (4), setiform, smooth. Pedotecta I represented by large and broad scales, pedotecta II are small scales, broadly triangular, rounded distally in ventral view. Discidia triangular, rounded distally.

Anogenital region (Figs 1B, 2B, 3B) — With indistinct concavities and ridges. Four pairs of genital, one pair of aggenital and two pairs of anal setae short (4–6) setiform, smooth. Three pairs of adanal setae (ad ₁, ad ₂, 6–8; ad ₃, 4–6) slightly phylliform, smooth, ad ₁, ad ₂ inserted on the arch-like ridge posterior to the anal aperture. Adanal lyrifissures not discerned under the cerotegumental layer.

Legs (Figs 4A–D) — Claw of each leg strong, smooth. Porose areas of femora and 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 (1–2–2–2–11) [0–1–0]; homology of setae and solenidia indicated in Table 1. Famulus of tarsi short, erect, blunt-ended, inserted proximal to ω₁. Solenidion φ₁ of tibiae I long, setiform, other leg solenidia thickened, blunt-ended. Setae l” of genua I, II strongly dilated distally (palmate), barbed.

Type deposition — The holotype (ethanol with drop of glycerol) is deposited in SMNH; one paratype (ethanol with drop of glycerol) is deposited in TSUMZ.

Etymology — The specific name minutus refers to the small body size of the new species.

Comparison — The new species differs from all species of the genus by the localization of notogastral setae lm and h ₂ in same longitudinal row together with da, dm, dp, lp and h ₁ (versus lm and h ₂ inserted in dorsolateral position, setae da, dm, dp, lp and h ₁ inserted in dorsocentral position).

1. Bothridial setae thickened, without distinct heads; notogastral tubercles forming polygonal pattern; body size: 295–379 × 138–170
...... Hardybodes penicillatus Mahunka, 1995 (see also Fernandez et al. 2015). Distribution: Borneo.

— Bothridial setae with well-developed spathulate heads; notogastral tubercles not forming polygonal pattern
...... 2

2. Notogastral setae lm and h ₂ inserted dorsocentrally in the same longitudinal row together with da, dm, dp, lp, h ₁; body size: 281 × 135–143
...... Hardybodes minutus n. sp. Distribution: Philippines.

— Notogastral setae lm and h ₂ inserted in dorsolateral position, setae da, dm, dp, lp, h ₁ inserted in dorsocentral position
...... 3

3. Notogaster tuberculate; rostral setae simple, lamellar setae bifurcate; body size: 324 × 146
...... Hardybodes mirabilis Balogh, 1970 (see also Fernandez et al. 2013). Distribution: New Guinea, Philippines, Borneo.

— Notogaster not tuberculate; rostral and lamellar setae phylliform; body size: 266–319 × 123–153
...... Hardybodes flabellatus Mahunka, 1995. Distribution: Borneo.

We cordially thank Dr. Umukusum Shtanchaeva (Universidad Complutense de Madrid, Madrid, Spain) and anonymous reviewer for the valuable comments; and R. Garcia, J. Naredo and H. Klompen for collecting materials used in this study; and J. Naredo for facilitating transmittal of the specimens, together with other oribatids, to Russia.

Balogh J. 1970 — New oribatids (Acari) from New Guinea. II — Acta Zool. Acad. Sci. Hung., 16(3-4): 291-344.

Corpuz-Raros L.A. 1979 — Philippine Oribatei (Acarina). I. Preliminary list of species and descriptions of forty new species — Philip. Agr., 62(1): 1-82.

Fernandez N., Theron P., Rollard C. 2013 — The family Carabodidae (Acari: Oribatida) I. Description of a new genus, Bovicarabodes with three new species, and the redescription of Hardybodes mirabilis Balogh, 1970 — Int. J. Acar., 39(1): 26-57. doi:10.1080/01647954.2012.741144

Fernandez N., Theron P., Rollard C., Leiva S. 2015 — The family Carabodidae (Acari: Oribatida) IX. Redescription of Carabodella calcarata Mahunka, 1986 and Hardybodes penicillatus Mahunka, 1995 — Int. J. Acar., 41(7): 551-562. doi:10.1080/01647954.2015.1081406

Mahunka S. 1986a — A survey of the family Carabodidae C.L. Koch, 1836 (Acari: Oribatida) — Acta Zool. Hung., 32(1-2): 73-135.

Mahunka S. 1986b — Oribatids from Africa (Acari: Oribatida) III — Folia Ent. Hung., 47(1-2): 41-76.

Mahunka S. 1987 — Neue und interessante Milben aus dem Genfer Museum LX. Oribatids from Sabah (East Malaysia) II. (Acari: Oribatida) — Rev. Suisse Zool., 94 (4): 765-817. doi:10.5962/bhl.part.79551

Mahunka S. 1995 — Oribatids from Brunei I (Acari: Oribatida) (New and interesting mites from the Geneva Museum LXXV) — Rev. Suisse Zool., 102(4): 913-942.

Norton R.A. 1977 — A review of F. Grandjean's system of leg chaetotaxy in the Oribatei (Acari) and its application to the family Damaeidae — In: Dindal D.L. (Ed.). Biology of oribatid mites. Syracuse: SUNY College of Environmental Science and Forestry. pp. 33-61.

Norton R.A., Behan-Pelletier V.M. 2009 — Oribatida. Chapter 15 — In: Krantz G.W., Walter D.E. (eds.). A Manual of Acarology. Lubbock: Texas Tech University Press pp. 430-564.

Subías L.S. 2004 — Listado sistemático, sinonímico y biogeográfico de los ácaros oribátidos (Acariformes: Oribatida) del mundo (excepto fósiles) — Graellsia, 60 (número extraordinario): 3-305. Online version accessed in February 2017, 598 pp.; http://escalera.bio.ucm.es/usuarios/bba/cont/docs/RO_1.pdf

Travé J., Vachon M. 1975 — François Grandjean. 1882-1975 (Notice biographique et bibliographique) — Acarologia, 17(1): 1-19.