Mixacarus turialbaiensis, Fernandez, Nestor, Theron, Pieter, Leiva, Sergio & Tiedt, Louwrens, 2017

Fernandez, Nestor, Theron, Pieter, Leiva, Sergio & Tiedt, Louwrens, 2017, Two new Oribatid mites from Costa Rica, Mixacarusturialbaiensis sp. n. and Paulianacaruscostaricensis sp. n. (Acari, Oribatida, Lohmanniidae), ZooKeys 680, pp. 33-56 : 33

Mixacarus turialbaiensis sp. n. Figs 1-8, 9-11, 12-15, 16-18, 19-23, 24-28; Table 1

Etymology.

The specific epithet is dedicated to the Turrialba forest of Costa Rica, where the specimens were collected.

Type material.

Holotype. Label details: "CCR 0978 Tu 11 Costa Rica Turrialba forêt naturelle du catie alt. 560 m. Triage d’humus cote est surface nid d’Atta au pied de Castilla elastica 1.IX. 1978. LEG P.WERNER 10.140744, alt. 120 m" conserved in 70% ethanol, deposited in MHNG.

Paratypes. same data, 2 ♀♀ deposited in MHNG; preserved in 70% ethanol.

Diagnosis

(adult female). Setae ro inserted anteriorly on transversal cuticular ridge; le, in setae erect; setae ro, le, in more or less similar length. Several ribbon-like bands near ro, le, exa, exp setae; sensillus pectinate (6-9 pectines); clearly visible superior cornea of naso (CSO).

Sixteen pairs of setae: c1, c2, c3, d1, d2, d3, e1, e2, f1, f2, h1, h2, h3, p1, p2, p3; eight transversal bands: S2, S3, S4; S5, S6, S7, S8, S9. Bands S2, S6, S8, S9 cross medial notogastral plane transversally; S3, S4, S5, S7 not crossing medial notogastral plane. Five pairs of lyrifissures: ia, ip, ips, im, ih.

Adoral setae: or1 spoon-shaped, largest; or2 elongate, tip beak-shaped; or3 large, rounded apex. Epimeral setal formula 3 –1–3–(3– 4), epimere IV with either three or four pairs of setae; genital plate undivided, rounded elevated central zone bearing nine or ten pairs of setae; six or seven pairs of simple setae aligned paraxially,

Description

(female).Measurements. 525 (485-560) × 233 (224-245) (ten specimens measured).

Shape. Oval (Figures 1, 9, 10, 12).

Colour. Yellow to light brown; slightly shiny when observed in reflected light.

Cerotegument. Almost nonexistent; or disappeared during extensive period of conservation in ethanol.

Integument. Smooth: prodorsum, notogaster, ventral region (Figures 1, 12); depressed areas of variable size with polyhedral microsculpture (Figure 7): sb (ribbon-like prodorsal bands) (Figure 1); lateral prodorsal zone (Figures 5, 6); zone of l.d (Figures 8, 13, 14); notogastral band S2, S3, S4, S5, S6, S7, S8, S9 (Figures 1, 2, 9, 11, 12, 19); notogastral marginal zone (Figures 12, 19); subcapitular zone around setae h, m1, m2, a (Figure 20); epimeral zone (Figures 16, 17, 21, 23); anogenital zone (Figure 18); ventral zone external to anogenital zone (Figures 16, 18); legs (Figures 24-28).

Setation (legs not included). Two types: simple, smooth: genital, anal (Figures 1, 2, 18); simple, barbed: prodorsum, notogaster, epimeral, subcapitular (Figures 3, 4, 5, 14, 21, 23). Barbs are small, difficult to observe.

Prodorsum. Shape: triangular, rounded apex in dorsal view (Figures 1, 9); triangular in lateral view (Figures 12, 14). Rostrum broadly rounded (Figures 1, 9); elevated chitinous ridge present on either side of prodorsal area, externally to exa, exp, le setae, derived from margins of leg depressions (Figures 12, 14); ro setae inserted anteriorly on transversal cuticular ridge, generally directing forward (Figures 1, 9, 12); le, in setae erect (Figure 12); setae ro, le, in more or less similar length. Several ribbon-like bands near ro, le, exa, exp setae, extending laterally to elevated lateral ridge (Figures 5, 6, 12, 13). Bo rounded, slightly elevated from the cuticular surface (Figure 15), laterally tilted (Figures 1, 9, 12). Sensillus pectinate (6-9 pectines) (Figures 9, 11, 12). Postbothridial transverse band sb clearly discernible, situated posterior to bo and in setae (Figures 1, 9, 11). On anterior zone near apex, in front of ro setal insertion and between cuticular elevations of l.d, CSO clearly visible (Figures 1, 12, 14).

Notogaster. Sixteen pairs of primary notogastral setae: c1, c2, c3, d1, d2, d3, e1, e2, f1, f2, h1, h2, h3, p1, p2, p3 clearly discernible (Figures 1, 9, 11, 12). Nine transversal bands: S2, S3, S4, S5, S6, S7, S8, S9 (Figures 1, 9, 11, 12); S2 crossing transverse medial notogastral plane, exceeding slightly beyond c2 setae, terminating near c3 in a large rectilinear tip (Figures 11, 12); S3 situated behind c setal alignment and in front of d setal alignment, not crossing medial notogastral plane; laterally stopping above c3, d3 setal insertion level (Figures 11, 12); S4 observed anterior to d setal alignment, not crossing medial notogastral plane, running obliquely, exceeding d1 setal insertion level, terminating in rounded end (Figures 1, 9); S4 extending to unsclerotized lateral longitudinal line (Figures 11, 12); S5 thin (Figures 1, 9), not crossing medial notogastral plane, laterally terminating before d3 setal insertion level (Figures 11, 12); S6 situated behind e1, crossing medial notogastral plane (Figures 1, 9), laterally reaching unsclerotized lateral longitudinal line (Figures 1, 9, 11, 12); S7 situated behind f1 setal insertion, not crossing medial notogastral plane, extending to unsclerotized lateral longitudinal line (Figures 1, 9, 11, 12); S8, S9 crossing medial notogastral plane and unsclerotized lateral longitudinal line (Figure 11).

Five pairs of lyrifissures present: ia, ip situated below the unsclerotized lateral longitudinal line (see Lateral region); ips situated on the adanal fold band (BPDA) (Figures 9, 10, 11); im near e2 setae and ih behind h3.

Lateral region. Prodorsal margin present on either side of cavities housing legs I-IV when retracted. Anterior notogastral zone presenting conspicuous tectum and clearly defined unsclerotized lateral longitudinal line, terminating almost posterior to level of ip lyrifissure and delimiting unpaired dorsal notaspis and pleuraspis (paired narrow lateral zones) (Figure 11). In posterior notogastral zone, when unsclerotized line does not exist, notaspis and pleuraspis not delimited (Figure 11). Each pleuraspis presenting an anterior rounded lobe between legs II and III, where lyrifissure ia is observed. Posteriorly, at level of d3 and e2 setae, well delimited edges form canopies over cavities in which legs III and IV are housed when retracted, with a protruding angle between them.

Ventral region. Anterior zone of subcapitulum more or less triangular, posterior zone ovoid. Four pairs of subcapitular setae (Figure 10) h, m1, m2, a. Characteristic adoral setae: or1 largest, spoon shaped; or2 elongate, terminating in beak-shape; or3 large, rounded apex (Figure 20).

Coxisternal region divided into two parts by ventrosejugal groove (Figures 10, 16, 17). Apodemes short and clearly visible; epimeral setal formulae 3-1-3-(3-4), epimere IV with three or four pairs of setae; all setae similarly shaped, but vary in length (Figures 21, 22, 23). Genital plate undivided, elevated central zone rounded with ten pairs of setae, sometimes with only nine pairs; (Figures 10, 16, 18); six or seven simple setae aligned paraxially, and three antiaxially. Preanal plate more or less triangular, rounded central zone.

Anal and adanal plates with four pairs of adanal and two pairs anal setae (Figures 16, 18). Band BPAD clearly visible in specimens immersed in lactic acid for lengthy period; lyrifissure ips present near margin of this band (Figure 10).

Legs. Two types of femora can be distinguished. Femora of legs I and II displaying large ventral blade (Figures 24, 25), femora of legs III and IV lacking ventral blade (Figures 26, 27).

Setal formulae I (0 –3–2–2–16– 1) (2 –1– 2); II (0 –4–2–3–13– 1) (1 –1– 1); III (2 –3–2–2–13– 1) (1 –1– 0); IV (2 –3–2-3–13–1(1–0– 0). See Table 1.