Malgasodes curvisetus Mahunka, 2000

Fernandez, Nestor, Theron, Pieter, Rollard, Christine & Castillo, Elio Rodrigo, 2014, Revision of the family Carabodidae (Acari, Oribatida) VII. Redefinition of the genus Malgasodes; redescription of M. curvisetus Mahunka, 2000; and complementary description of M. hungarorum Mahunka, 2010. Phylogenetic relationships between Malgasodes, Bovicarabodes, Afticarabodes, Congocepheus and Cavaecarabodes are discussed, ZooKeys 435, pp. 25-48 : 27-35

Taxon classification Animalia Oribatida Carabodidae

Malgasodes curvisetus Mahunka, 2000 Figures 1-17

Diagnosis.

Redescription. Shape: elongate ovoid.

Integument. Prodorsum and notogaster smooth; only zone surrounding superior eye cornea, bothridium, and lateral body with small protuberances.

Setation.simple, small: subcapitular, epimeric, genital, aggenital, anal, adanal; simple, large, long sharply curving tip: notogastral, surrounding, posterior to and inside notogastral anterior depression and in setae; sausage-shaped, roughly-spiculate surface: le setae; phylliform, small, elevated central zone: ro setae; phylliform medium sized: h3, p1, p2, p3.

Prodorsum. Triangular to polyhedral. Intact elevated interlamellar process; in setae situated on elevated interlamellar process. Setae in, ro, le different shapes and lengths: in> le> ro; in setae directing posteriorly, exceeding the prodorsal margin. Rostral margin rounded. Shallow lamellar furrow discernible in the proximity of lamellar tip; lamellar tip triangular, small, shark tooth-like shape; superior cornea of naso, clearly visible; sensillus uncinate, curving upward. Notogastral anterior depression zone rectangular; posterior to this rectangular zone, an ovoid zone; dorsosejugal furrow hardy discernible, narrow, curving slightly backward. Circumgastric depression present, hardly discernible. Two pairs of notogastral setae situated posterior to notogastral anterior depression, extending forward. Four pairs inside notogastral anterior depression, with two pairs situated near dorsosejugal furrow, extending backward; four pairs bordering notogastral anterior depression, extending forward; four pairs marginally to notogaster, directing backward; three pairs of lyrifissures present, one pair at level of h3 setae; one pair anterior to p3 setae and ips between p1 and p2 setae.

Apodemes apo.1, apo.2, apo.sj and apo.3 clearly visible; at level apo.1, in medial zone, rounded structure visible. Four pairs of linearly placed genital setae. Aggenital setae posterolaterally, three pairs of adanal setae; small, elongate bean-shaped lyrifissures iad. Two pairs of anal setae. Smooth surface between genital and anal openings.

Material examined.

Scanning Electron Microscopy and optic observation: 6 specimens; Madagascar R.C.P 2010. «Région Fort-Dauphin Madagascar Sud-est." "R.C.P 2010-Piste de Ste Luce-Forêt littorale-Altitude 10 mètres» 9-12-1971. Coll. J-M.BETSCH. Three specimens deposited in Muséum National d’Histoire Naturelle, (MNHN) Paris, France.

Adult description.

Female. Measurements: 372 μm (400-351) × 260 μm (239-281) (three specimens). All specimens were female.

Shape: elongate ovoid (Figures 1, 4, 5).

Colour: yellow to light brown; slightly shiny, when observed in reflected light.

Cerotegument. Present in the notogastral anterior depression (n.a.d), retained by the setae and on humeral apophysis. On other body parts and legs nonexistent or disappeared during observation in lactic acid; similar in SEM observations (Figures 1, 6).

Integument. Prodorsum: elevated interlamellar process (e.i.p) smooth (Figures 1, 2, 6); zone surrounding CSO, bo, and lateral body zone with small protuberances (Figures 7, 8, 10). Notogaster: smooth (Figures 1, 3, 6).

Setation (legs not included). Five types: 1) simple, small: subcapitular, epimeric, genital, aggenital, anal, adanal (Figure 5); 2) simple, large, long sharply curving tip: notogastral setae around, behind and inside n.a.d, and in setae (Figures 1, 2, 3, 4, 6); 3) sausage-shaped, roughly-spiculate surface: le (Figure 7); 4) phylliform, small, with elevated central zone, delimited on both sides by longitudinal depression; central elevated zone with longitudinal furrow in central zone giving a particular aspect in frontal view (Figure 10): ro setae (Figures 2, 7, 17); 5) phylliform, medium size: notogastral h3, p1, p2, p3 (Figures 1, 3, 4, 6, 12, 14).

Prodorsum. Triangular to slightly polyhedral (dorsal view) (Figures 1, 4); triangular in lateral and frontal view (Figures 2, 6, 12). Entire elevated interlamellar process (e.i.p) (Figure 2) situated at lower level than superior notogastral limit (Figures 2, 3, 6, 12).

Posterior prodorsal depression (p.p.d) absent (Figures 1, 6). Setae in situated on e.i.p (Figures 1, 2, 4, 6, 12), similar characteristics to long simple notogastral setae situated near and inside n.a.d; in all cases the in setae directing backward and entangled with cited notogastral setae (Figures 1, 2, 4, 6, 12).

Three pairs of prodorsal setae (in, ro, le) very different in shape and length (see Setation): in> le> ro; ro setae small, inserted posteriorly to le insertion, directing forward (Figures 1, 2, 4, 7, 10, 12, 14); in setae inserted on e.i.p antiaxially to medial plane and slightly externally to ro insertion level; posteriorly directed, far exceeding the prodorsal margin extending to n.a.d (Figures 1, 2, 4, 12, 19); le setae (Figures 1, 2, 4, 7, 10, 12, 14) laterally situated on lamellar apical zone but far from lamellar tip (la.ti), directing forward with tips converging to medial plane; le setae always found on prodorsal surface. Rostral margin rounded (Figures 1, 2, 4, 7, 10). Lamellae running laterally; shallow lamellar furrow (l.l.f) only discernible in proximity of la.ti (Figure 17); la.ti more or less triangular, small, sharply tipped (Figure 17). In frontal view (Figures 2, 10) the superior cornea of naso (cso) is clearly visible as a convex elevation situated anterior to the ro setal insertion; upward curving sensillus (si) uncinate with small barbs (Figure 2, 4, 6, 8, 12, 15).

Bothridium (bo), round–ovoid; bothridial ring (bo.ri) smooth, with bothridial tooth (bo.to), clearly visible (Figure 8, 12, 15).

Notogaster. In dorsal view, zone of n.a.d rectangular; posterior to this zone, ovoid (Figures 1, 4); in lateral view anterior part (zone of n.a.d) depressed, concave whilst rest of notogaster convex (Figure 6, 12); d.sj hardly discernible, narrow, curving slightly backward.

Notogaster smooth (Figures 1, 3, 6, 12). Anterior notogastral depression (n.a.d) ovoid, conspicuous, large, extending forward (Figures 1, 4, 6, 12).

Circumgastric depression (s.c) present, hardly discernible (Figure 1, 3), situated at notogastral lateral setal insertion level (p1, p2, p3, h3).

Fourteen pairs of notogastral setae, two pairs situated posterior to n.a.d, extending forward, exceeded d.sj; four pairs inside n.a.d, of which two pairs situated near d.sj extending backward (indicated in Figure 4, 19 with X); two pairs situated far from d.sj, extending forward, exceeding d.sj (one of them indicated in Figure 4, 19 with J); four pairs situated marginally to n.a.d, extending forward, exceeding d.sj and four pairs, situated marginally to notogaster, directing backward, these pairs we named h3, p1, p2, p3 (Figures 1, 3, 4, 6, 12, 14, 19).

Lyrifissures difficult to observe; three pairs present, first pair situated at level of h3 setae (Figure 12), another situated anterior to p3 setae and ips situated between p1 and p2. Lyrifissures not visible in SEM, only under optic observation (Figures 12, 14).

Humeral apophysis (h.ap) clearly discernible principally in lateral view (Figures 1, 4, 6, 8, 12, 19), antiaxially aligned irregular furrows (a.i.f) present, permitting concealment of si during protection mechanism deployment (Figures 6, 19, indicated by arrows). Cerotegumental layer often covering h.ap (Figures 6, 8, 19). The h.p and the posterior bothridial zone in the junction zone between both structures, posterior bothridial tip overlapping h.ap anterior margin (Figure 6, 12, 19). Tectum border remarkable, not prolonged by a limbus, but by transverse cuticular structure (Figure 13 indicated by X) delimiting a space between notogastral and ventral shield (indicated by arrows· Figures 6; 12, 13, 19).

Lateral region. Tutorium (tu) clearly visible as a strongly curving cuticular thickening. Between lamellae and tutorium a deep supratutorial depression (s.tu.d) running parallel to both structures (Figures 6, 7, 12, 19). Bothridia cup-shaped with smooth bothridial ring (bo. ri); bo.ri incomplete with bothridial tooth (bo.to) clearly visible (Figures 8, 12, 15, 19); sensillus (si) uncinate with small barbs, curving upward (Figures 8, 15) tip usually pointed, more coarsely barbed on lateral edge.

Lamellae with la.ti, short, "shark tooth-like" (Figures 7, 17); le setae sausage-shaped (Figure 17), roughly-spiculate surface, clearly visible (Figure 17 indicated by arrowh); ro phylliform, with rounded elevated central zone, delimited on each side by, depressed longitudinal furrow (Figure 17); n.a.d well discernible due to transparency (Figure 12); two pairs of setae (probably c1, c2) situated in the anterior part of n.a.d and close to d.sj, (Figures 4, 6, 12, 19 indicated by X), observating d.sj, complicated by presence of cerotegument and setae, requiring observation from different angles. Two other pairs of setae situated inside n.a.d; first pair laterally and close to two anterior setae, at level of bothridia (Figures 4, 12, 19 indicated byJ); the second pair hardly discernible, easily confused with other setae, situated marginally to n.a.d. Lateral view permitting clear understanding, of different setae directions and perceiving the complexity found at n.a.d level (Figures 6, 12, 19).

Pedotectum I, prominent extended lamina. Pedotectum II, small polyhedral lamina, rounded edges. Humeral apophysis more or less triangular; basally slightly convex, immediately becoming concave; posterior bothridial zone overlapping anterior tip (Figure 12); aligned irregular furrows (a.i.f) delimited by rod-like cuticular structures (Figures 6, 19, indicated by arrow), crossing h.ap.

SEM observations made from two different lateral angles (Figures 6, 19) in order to clarify the relative position, shape and disposition of different prodorsal and notogastral structures and setae. In order to show positioning of legs during "legs folding process’ specimens are shown with legs in place and alternatively with distended legs. Only one lyrifissure visible at level of h3 setae Discidium not discernible. Only one depression, situated behind leg IV, used conceal tibia and tarsus (paraxial side) (Figure 6 indicated by X) during leg folding process (see Fernandez et al. 2013b).

Posterior view. Posterior view (Figure 14) clarifying position of marginal setae p1, p2, p3, lyrifissures and the two pairs of notogastral setae situated posterior to n.a.d, unique pairs visible in posterior view. Lyrifissure ips can be uniquely identified on account of placement between setae p1 and p2; the other, probably ih, situated between p3 and h3.

In this position the zone between ventral and notogastral figs is easily discernible, separated due to particular tectal border (indicated in Figure 14 by ·).

Ventral region. Subcapitulum with three pairs of setae (a, m, h) clearly visible; insertion zone m and a setae simple, smooth (Figures 16, 18). Epimera hardly discernible; only bo.sj clearly visible as shallow furrow crossing the medial plane (Figure 16).

Apodemes apo.1, apo.2, apo.sj and apo.3 clearly visible (Figure 5). In median zone, at level of apo.1, rounded more sclerotized structure visible (in optic observation), but smooth under SEM observation. Epimeral chaetotaxy 3-1-3-3.

Genital fig more or less similar in size to anal fig (Figure 5); anal fig small, sharply tipped (Figure 16); paraxial border of anal figs with small teeth (Figure 5, indicated by 5) on anterior third.

Anterior to genital fig a furrow (a.g.f) clearly visible. Four pairs of linear genital setae. Aggenital setae posterolaterally, posterior opening of genital border (Figure 5) situated at same level or slightly antiaxially to ad 3 setal insertion. Three pairs of adanal setae; small elongate bean-shaped lyrifissures iad clearly visible, situated antiaxially and far from ad3. Two pairs of anal setae. Smooth surface between and lateral to genital and anal openings (Figure 16); depression at level of leg IV (involved in leg folding process. See lateral region). Short, curving, cuticular thickening behind acetabulum IV (Figure 5 indicated by X).

Legs. Legs presenting all characteristics observed in other Carabodidae , but lateral setae of genua are particular (Figure 11). The (u) pair of all tarsi are without barbs but rugous, particular (Figure 9).

All structures related to leg folding are present ( Fernandez et al. 2013a) and clearly visible (Figures 6, 12, 16, 19).

Setal formulae I (1-4-3-4-15-1) (1-2-2); II (1-4-3-3-15-1) (1-1-2); III (2-3-1-2-14-1) (1-1-0); IV (1-2-2-1-12-1) (0-1-0).

Remarks.

Anterior part of n.a.d extending to d.sj, together with notogastral setae situated in this zone preventing clear observation. The e.i.p. is an elevated process situated not far from d.sj. The posterior part of e.i.p descending steeply at d.sj level. We consider p.p.d to be absent.

Two pairs of setae situated close to d.sj are probably c1,and c2 setae, but without immature stases it was impossible to establish with certainty.

Border of tectum in Malgasodes is unlike all others; in that it is not prolonged by a limbus, and that a space exists between the ventral fig and the notogaster.

Various inclinations in lateral view are provided to permit better understanding of the disposition of notogastral setae and the steeply descending posterior part of e.i.p towards d.sj.