Galumna acutirostrum, Ermilov, Sergey G. & Anichkin, Alexander E., 2010

Ermilov, Sergey G. & Anichkin, Alexander E., 2010, Three new species of Galumnidae (Acari: Oribatida) from Cat Tien National Park, southern Vietnam, Zootaxa 2681, pp. 20-34 : 21-25

Galumna acutirostrum sp. nov.

( Figs. 1–22 )

Diagnosis. With character states of Galumna as summarized by Balogh and Balogh (1992). Distinguished from other species by combination of the following character states: body size 747–846 × 630–680; surface of body smooth; rostrum pointed in dorsoventral view; rostral (ro, 65–69), lamellar (le, 118–127) and interlamellar (in, 135–143) setae setiform, slightly barbed; sensilli (ss, 135–143) nearly setiform, slightly fusiform, with indistinct head having several very small barbs; dorsosejugal suture incomplete; four pairs of rounded or slightly oval notogastral areae porosae; median pore (mp) present; oval postanal area porosa (Ap) present.

Description. Measurements. Body length 796 (holotype), 747–846 (paratypes); body width 630 (holotype), 630–680 (paratypes).

Integument. Body color brown to dark brown. Surface of body smooth.

Prodorsum ( Figs. 1, 3 , 6–9 ). Rostrum pointed in dorsoventral view. Lamellar and sublamellar lines well developed. Rostral (65–69), lamellar (118–127) and interlamellar (135–143) setae setiform, slightly barbed. Lamellar lines with one small tooth; basal part of lamellar setae under this tooth ( Fig. 7 ). Sensilli (135–143) nearly setiform, weakly fusiform, with head indistinct; distal part with several very small barbs. Exobothridial setae not observed. A pair of oval areae porosae Ad present posterior to interlamellar setae.

Notogaster ( Figs. 1, 4, 5 , 10–13 ). Dorsosejugal suture incomplete. Notogastral setae absent (represented only by 10 pairs of alveoli). Four pairs of areae porosae developed dorsally: Aa oval, 36–41 × 24–32; A1 and A2 rounded, diameter 24–28; A3 rounded or slightly oval (diameter 28–32). Median pore present in all specimens (female and male), situated behind level of areae porosae A3.

Anogenital region ( Figs. 2 , 14–17 ). Two pairs of anal (an 1, an 2), three pairs of adanal (ad 1– ad 3), one pair of aggenital (ag) setae very small (8). Six pairs of genital setae longer (g 1– g 6, 24–28), thin, slightly barbed. Anterior part of genital plates with two setae (g 1, g 2). Ovipositor elongate, narrow (335 × 82). Length of lobes 143, length of cylindrical distal part 192. Setae smooth, ψ1 ≈ τ1 (86) longer than ψ2 ≈ τ a ≈ τ b ≈ τ c (32). Setae k short (8). Oval postanal area porosa (41–49 × 20–28) present.

Epimeral region ( Fig. 2 ). Only four pairs of setiform, thin epimeral setae (24–32) observed. Epimeral setal formula: 1–0–2–1.

Gnathosoma ( Figs. 18–20 ). Subcapitulum longer than wide: 184 × 164. Hypostomal setae a, m, h setiform, slightly barbed; h (36–41) longer than a (28–32) and m (24). Two pairs of setiform, curved, barbed adoral setae (16). Palp (length 155) with setation 0–2–1–3–9(+1ω). All setae (except on tarsus) barbed. Chelicera (length 221–233) with few blunt teeth on fixed and movable digits. Cheliceral setae long, setiform, barbed: cha (73–77) longer, than chb (45–53).

Legs ( Figs. 21–22 ). Formulas 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. Almost all setae well barbed; some ventral setae of tarsi and tibiae with long cilia. Solenidia ω1 and ω2 on tarsi II, σ on genua III straight or weakly curved, rod-like. Other solenidia rather long, setiform, with thinner tips.

Material examined. Holotype, paratypes (three specimens). Specimens were obtained from: Asian region, southern Vietnam, 11º26'N, 107º26'E, Cat Tien National Park, 137 m above sea level, in sandy soil of dipterocarp forest, February – March 2009, collected by A.E. Anichkin.

Type deposition. The holotype is deposited in the collection of the Zoological Institute of the Russian Academy of Sciences, St. Petersburg, Russia; two paratypes are deposited in the collection of Siberian Zoological Museum, Novosibirsk, Russia; one paratype are in the personal collection of the first author. Etymology. The name “ acutirostrum ” refers to the pointed rostrum.

Distribution. At present, this species is only known from Cat Tien National Park of southern Vietnam.

Leg Trochanter Femur Genu Tibia Tarsus

I v' d, (l), bv'' (l), v', σ (l), (v), φ1, φ2 (ft), (tc), (it), (p), (u), (a), s, (pv), v', (pl),

l'', e, ω1, ω2

II v' d, (l), bv'' (l), v', σ (l), (v), φ (ft), (tc), (it), (p), (u), (a), s, (pv), ω1, ω2

III v' d, ev' l', σ l', (v), φ (ft), (tc), (it), (p), (u), (a), s, (pv)

IV v' d, ev' d, l' l', (v), φ ft'', (tc), (p), (u), (a), s, (pv)

*Roman letters refer to normal setae, Greek letters refer to solenidia, e – famulus. One apostrophe (') marks setae on anterior and double apostrophe (") setae on posterior side of the given leg segment. Parentheses refer to a pair of setae.

Remarks. In having the combination of a pointed rostrum, long prodorsal setae (ro, le, in), nearly setiform sensilli, incomplete dorsosejugal suture, and four pairs of notogastral areae porosae, G. acutirostrum is similar only to Galumna grandjeani Balogh, 1962 from Central Africa ( Balogh 1962). It differs from the latter by having smaller, rounded or oval notogastral areae porosae (large notogastral areae porosae, A1 triangular, A2 and A3 obviously oblonged in G. grandjeani ) and the presence of a single postanal area porosa (two in G. grandjeani ). Galumna acutirostrum sp. nov. in having the combination of a pointed rostrum, long prodorsal setae, incomplete dorsosejugal suture, four pairs of notogastral areae porosae is similar to Galumna valida Aoki, 1994 from Micronesia, but differs from later by larger body size (747–846 × 630–680 in new species; 705–760 × 600–630 in Galumna valida ); lamellar setae shorter than interlamellar setae (lamellar setae longer than interlamellar setae in Galumna valida ); setiform, thickened sensilli without sensillar head (sensilli with spindle-shaped sensillar head in Galumna valida ).

Figures

FIGURES 1 – 5. Galumna acutirostrum sp. nov.: 1 — dorsal view, 2 — ventral view, legs removed, 3 — dorso-lateral view of prodorsum, 4 — pteromorpha, 5 — caudal view. Scale bar (1 – 2, 5) 200 μm, scale bar (3 – 4) 100 μm.

FIGURES 6 – 17. Galumna acutirostrum sp. nov.: 6 — rostral seta, 7 — lamellar seta, 8 — interlamellar seta, 9 — sensillus, 10 — area porosa Aa, 11 — area porosa A 1, 12 — area porosa A 2, 13 — area porosa A 3, 14 — postanal area porosa; 15 — genital plate, right, 16 — anal plate, right, 17 — ovipositor. Scale bar (6 – 9, 15 – 17) 50 μm, scale bar (10 – 14) 20 μm.

FIGURES 18 – 22. Galumna acutirostrum sp. nov.: 18 — subcapitulum, 19 — palp, 20 — chelicera, 21 — leg I, without trochanter, left, antiaxial view, 22 — leg IV, left, antiaxial view; Ti, Ge – tibiae, genua, accordingly. Scale bar (18, 20) 50 μm, scale bar (19) 20 μm, scale bar (21 – 22) 100 μm.