Galumna (Galumna) sandormahunkai, Ermilov & Starý, 2020

Ermilov, Sergey G. & Starý, Josef, 2020, New and interesting species of the generaGalumna andPergalumna (Acari, Oribatida, Galumnidae) from the Montagne d’Ambre National Park, Madagascar, Acarologia 60 (1), pp. 64-74 : 64-74

Galumna (Galumna) sandormahunkai n. sp.

Zoobank: 98E9F2F2-5384-4E4D-BADE-C6A461B64755

( Figures 1–3 )

Diagnosis — Body size 780–996 × 564–780. Rostrum protruding, narrowly rounded. Lamellar and sublamellar lines divergent distally, L directed to lateral sides of prodorsum, S curving backwards. Rostral and lamellar setae of medium size, setiform, slightly barbed. Interlamellar setae minute. Bothridial setae long, narrowly lanceolate, barbed. Dorsosejugal porose areas present. Dorsosejugal suture complete. Four pairs of small porose areas, Aa oval, others rounded. Median pore absent. Epimeral setal formula 1-0-1-2. Epimeral and anogenital setae short, setiform, roughened. Circumpedal carinae short. Postanal porose area narrowly elongate oval. Solenidion on tibiae IV inserted in anterior part of the segment.

Description — Measurements – Large species. Body length 996 (holotype, female), 780– 996 (13 paratypes, 10 females and three males); notogaster width 763 (holotype), 564–780 (13 paratypes). Females larger than males: 946–996 × 747–780 versus 780–846 × 564–614.

Integument – Body color light brown to brown. Body surface densely microgranulate, granules (less than 1) poorly developed (visible only at high magnification x1000). Antiaxial sides of all leg femora and trochanters III, IV with rounded and elongated tubercles.

Prodorsum ( Figs 1a , 2a, 2c ) – Rostrum strongly protruding (visible in frontal view), narrowly rounded. Lamellar and sublamellar lines slightly divergent distally, L thickened, directed to lateral sides of prodorsum, S thin, curving backwards. Lateral structures N and ridges E and T well developed. Rostral (49–53) and lamellar (49–53) setae setiform, slightly barbed. Interlamellar setae very short (4–6), setiform, thin, smooth. Bothridial setae (159–168) with long stalk and short, narrowly lanceolate, barbed head. Exobothridial setae represented by alveoli. Dorsosejugal porose areas (24–32 × 4–6) elongate oval, transversely oriented, located posterior or posterolateral to in. Dorsophragmata slightly elongated longitudinally.

Notogaster ( Figs 1a , 2a, 2b ) – Dorsosejugal suture complete. With 10 pairs of setal alveoli or vestigial setae (up to 1) and four pairs of small porose areas having distinct borders, Aa (22–26 × 10–12) oval, A1, A2 and A3 (10–20) rounded. Porose areas Aa located close to pteromorphal hinges, anteriorly to la. Median pore absent in females and males. Opisthonotal gland openings and all lyrifissures distinct, gla located anterolateral to A1 and removed from them, im anterior to A1 and slightly removed from them, ip lateral to p 1, ih anterior to p 3, ips lateral to p 3.

Gnathosoma ( Figs 2 d-f) – Subcapitulum size 196–205 × 180–192. Subcapitular setae (a, 32; m, 32; h, 24) setiform, slightly barbed; a thickest, h thinnest. Adoral setae (24) setiform, barbed. Length of palps 139–143. Postpalpal setae (8) spiniform, smooth. Length of chelicerae 237–241. Cheliceral setae (cha, 82–86; chb, 45–49) setiform, barbed. Trägårdh’s organ of chelicerae long, elongate triangular.

Epimeral and lateral podosomal regions ( Figs 1b , 2a ) – Anterior margin of epimere I smooth. Epimeral setal formula 1-0-1-2. Epimeral setae setiform, thin, roughened, 3b (30–32) longer than 1b, 4a and 4b (18–20). Pedotecta I broadly rounded, pedotecta II quadringular in ventral view. Discidia triangular. Circumpedal carinae short, thin, directed to acetabula IV.

Anogenital region ( Figs 1b , 2b ) – Six pairs of genital setae g 1, (g 2, 26–28; g 3 – g 6, 18–20), one pair of aggenital (18–20), two pairs of anal (18–20) and three pairs of adanal (18–20) setae setiform, thin, roughened. Anterior edge of genital plates with two setae. Aggenital setae located between genital and anal apertures, nearer to genital aperture. Adanal lyrifissures located close and parallel to anal plates. Adanal setae ad 1 and ad 2 posterior, ad 3 lateral to anal aperture. Distance ad 1 – ad 2 slightly shorter than ad 2 – ad 3. Unpaired postanal porose area narrowly elongate oval (41–49 × 4–6).

Legs ( Figs 3a, 3b ) – Median claw distinctly thicker than lateral claws, all slightly barbed on dorsal side. Porose area on all femora and on trochanters III, IV well visible. Formulae of leg setation and solenidia I (1-4-3-4-20) [1-2-2], II (1-4-3-4-15) [1-1-2], III (1-2-1-3-15) [1-1-0], IV (1-2-2-3-12) [0-1-0]; homology of setae and solenidia indicated in Table 1 . Famulus on tarsi I inserted between solenidia ω 1 and ω 2. Solenidion on tibiae IV inserted in anterior part of the segment.

Material examined — Holotype (female) and 13 paratypes (10 females and three males): North Madagascar, Montagne d’Ambre National Park , circuit Ampijoroana , evergreen rain forest, 12°31’28”S, 49°09’52”E, 950 m a.s.l., sifting of leaf litter sample under big unidentified tree, Winkler apparatus extraction, 13.I.2014 (R. Ravebolun and L. Rabotenoson) .

Type deposition — The holotype and two paratypes are deposited in the collection of the Senckenberg Institute, Görlitz, Germany . Eleven paratypes are deposited in the collection of the Tyumen State University Museum of Zoology, Tyumen, Russia . All specimens are preserved in ethanol with drop of glycerol.

Etymology — The new species is named after late Prof. Dr. S. Mahunka, the Hungarian acarologist, for his extensive contributions to our knowledge of oribatid mites.

Remarks — In the presence of long rostral and lamellar setae, short interlamellar setae, long bothridial setae with developed head, complete dorsosejugal suture, and four pairs of rounded notogastral porose areas, Galumna sandormahunkai n. sp. is morphologically most similar to Galumna sphagni Ermilov, Hugo-Coetzee and Theron, 2018 from South Africa, but differs from the letter by the larger body size (780–996 × 564–780 versus 415–431 × 315–332), the presence of strongly protruding rostrum (versus not protruding), lanceolate, pointed apically bothridial setae (versus unilaterally dilated, rounded apically), the direction of lamellar lines to lateral sides of the prodorsum (versus anterior part of the ventral plate), and the absence of median pore (versus present).

Figures

Figure 1 Galumna sandormahunkai n. sp., adult: a – dorsal view; b – ventral view (gnathosoma and legs omitted). Scale bar 100 μm.

Figure 2 Galumna sandormahunkai n. sp., adult: a – anterior part of body, lateral view (gnathosoma and legs omitted); b – posterior part of body, lateral view; c – anterior part of prodorsum, frontal view; d – subcapitulum, ventral view; e – palp, right, antiaxial view; f – chelicera, left, paraxial view. Scale bar 100 μm (a, b), scale bar 50 μm (c, d, f), scale bar 20 μm (e).

Figure 3 Galumna sandormahunkai n. sp., adult: a – leg I, without trochanter, right, antiaxial view; b – leg IV, left, antiaxial view. Scale bar 50 μm.