Plasmobates zarae, Fernandez, Nestor & Theron, Pieter, 2016

Fernandez, Nestor & Theron, Pieter, 2016, Two new oribatid mites from the Republic of Rwanda. Plasmobateszarae sp. n. (Acari, Plasmobatidae) and Basilobelbaspasmenosi sp. n. (Acari, Basilobelbidae), ZooKeys 598, pp. 1-25 : 3-6

Taxon classification Animalia Sarcoptiformes Plasmobatidae

Plasmobates zarae sp. n. Figures 1-8, 9-13, 14-19, 20-24, 25-33, 34-42, Table 1

Etymology.

The specific epithet “zarae” is derived from (ζάρα, Grec=pucker, English) due to longitudinal pucker present on ro setae.

Material examined.

Holotype: Female and two paratypes (adult females): "73/2. Kayove-Rwanda; 2100 mts. 15/V/1973" Leg. P.Werner; deposited in the Collection of the Natural History Museum of Geneva (M.H.N.G), Switzerland; preserved in 70% ethanol. Material studied for SEM: three specimens, not deposited.

Diagnosis (adult female).

Cerotegumental layer. Amorphous: bothridial zone, tubercle of seta in, ro setae insertion, lateral gland, epimeral zone, genital plate and surrounding zone, anal plate and surrounding zone. Layer with small tubercles: internal bothridial zone. Mixed-layer (mushroom-like microtubercles associated with irregular cauliflower-like microtubercles): infracapitulum, epimeral zone, lateral body zone, basal zone lateral gland. Integument: prodorsum, small foveate to smooth; notogaster, foveate; ventral region rugose to smooth.

Setation: simple: lamellar, notogastral, exostigmatal, epimeral, genital, aggenital anal; whip-shaped, with longitudinal pucker: rostral setae; rod-shaped with triangular scales: interlamellar setae; simple, basally inflated: subcapitular a; simple spur: m.

Prodorsum: medial band extension on central part towards anterior, not extending to rostrum. Interlamellar setae inserted on large protuberances, lamellar setae small, rostral setae large, with longitudinal cuticular puckers, inserted on protuberances. Large horn-shaped bothridium, directing laterally, rectilinear wall with basally incised opening. Internal bothridial rings dentate. Whip-shaped sensillus with minute, triangular scales; exostigmatal seta small. Rostrum medially incised, posterior of incision rounded. Notogaster: fovea situated in smooth zone with circumgastrically distributed macropores on fovea margins or inside fovea. Opisthosomal gland apophysis flat, triangular in lateral view, cylindrical in posterolateral view. Six pairs of notogastral setae, all situated posterior to level of opistosomal gland. Lateral region: opening of podocephalic canal on large promontories.

Ventral region: epimeral setal formula (3-1-2-2). Seven pairs of genital setae; aggenital setae not detected. Three pairs of adanal setae, two pairs of anal setae. Scalps multilayered, medial band extending anteriorly from each scalp. Medial band covers central zone, firmly adhered to prodorsal surface. Nymphal scalps with dentate peripheral ridge. Setae hardly discernible, scalps simple without anterior tuft of filaments. Chinese hat-shaped larval scalp differing greatly from nymphal scalps

Description.

Measurements.SEM: total length with scalps 580-615 μm × 600 μm (measurements on three specimens). Total length without scalps 433-438 μm × 435μm (measurements on three specimens). Notogastral width without scalps 248- 253 μm × 250 μm. Light microscopy: 612-656 μm × 639 μm (measurements on three specimens). Specimens with scalps ovoid, elongate in dorsal view. (Figures 1, 9, 22). In lateral view specimens with scalps appear pyramidal (Figure 14); without scalps anterior triangular and posterior rounded (Figure 2).

Colour. Specimens without cerotegument and scalps dark yellowish to medium brown.

Cerotegument (scalps not considered). Thick complex layer with elaborate pattern, composed of wax layer and amorphous cement layer covering entire body and legs. Amorphous layer (Figure 33, indicated in all Figures with *): external bothridial zone of prodorsum (Figures 14, 15), tubercles of in setae (Figure 12), ro setae insertion zone (Figure 21), gla (Figure 18), epimeral zone (Figure 25) subcapitular setae h (Figure 26), genital plate and surrounding zone, anal plate and surrounding zone (Figure 32). Small tubercules: internal bothridial zone (Figure 16 indicated by5). Mixed-layer (Figures 28, 29, 30): mushroom-like microtubercles (mus) diameter 0.02-0.6 μm, height 0.2-1.9 μm associated with irregular cauliflower-like microtubercles (cau) diameter 1.2-1.9 μm, height 1.4-3.1 μm. Distribution: infracapitulum, epimeral zone, lateral body zone, basal zone of gla (Figures 18, 19, 25, 31). Legs: Trochanters covered by mixed-layer, femur, genu, tibia, covered by amorphous layer with prominent folds. Tarsus: amorphous layer with subtle folding and several smooth areas (Figures 14, 20, 35, 36, 38, 39, 42).

Integument. lateral microsculpture of prodorsum faintly foveate to smooth (Figures 1, 2, 3), dorsal microsculpture of prodorsum flat, foveate (Figure 7 indicated by h). Notogaster: foveate in vicinity of notogastral border (Figures 1, 2, 3), posterior notogastral zone smooth, posterolateral notogastral zone presenting ridges anterior to macropore zone (Figures 1, 2, 3). Distribution of macropores circumgastric (Figures 1, 2). Ventral region rugose to smooth on subcapitulum (Figure 25), epimeral zone, surrounding genital and anal openings and genital and anal plates.

Setation. Lamellar (Figure 4), notogastral, exostigmatal, epimeric, genital, aggenital (Figure 24) and anal setae simple; ro setae whip-shaped, with longitudinal pucker (Figures 9, 10, 11); in setae (10-13 μm) rod-shaped with triangular scales (Figure 12); subcapitular setae simple, slightly basally inflated (Figure 27) 30-36 μm a; h simple, spur-shaped (Figure 26) 16-21 μm.

Prodorsum. Medial band extension (m.b) observed on central part towards anterior, not extending to rostrum, terminating anterior to le setal insertion level on specimens with scalps (Figures 9, 13, 14, 20, 31). Elevated zone surrounding medial band extension (Figure 14). Interlamellar setae (in) inserted near bothridial base on large protuberances, extending upward and inclined backward (Figures 9, 12, 14, 15). Lamellar setae (le) small, inserted on small protuberances (Figure 4), rostral setae (ro) (58-61 μm) inserted on protuberances, cuticular folds at base of setae (Figures 10, 11, 14, 20, 21). Large laterally directing horn-shaped bothridium (Figures 14, 20). Semicircular lateral bothridial opening, basally incised with thin rectilinear wall (r.w) (Figures 14, 15). Internal bothridial rings dentate with triangular teeth (Figure 16).

Whip-shaped filiform sensillus (si) (80-106 μm) with minute triangular scales, height 196 nm, length 603-987 nm (Figure 17), exostigmatal setae (ex) small. Narrow medial incision on rostrum, in dorsal view posterior end of incision rounded (Figure 1).

Notogaster. Circumgastrically distributed macropores (mp) of varying diameter (0.3-1 μm) situated in small foveae on smooth zone, either on periphery or internally to foveated notogastral pattern (Figures 1, 2). In dorsal view anterior zone mp clearly visible (Figure 1), but those located near gla need to be observed in lateral or posterior views (Figure 2) due to notogastral shape, in order to obtain the best impression of their distribution.

Distribution of mp: a) single line in anterior notogastral zone; b) linear in anterior lateral zone near gla; c) irregularly distributed on posterior notogastral zone (setal zone) (Figure 1).

In dorsal view opisthosomal gland (gla) apophysis observed as flat triangle, but appears cylindrical in lateral and lateroposterior views, directing slightly obliquely forward (Figures 1, 9, 14, 18); opening with protuberances (Figure 18). Six notogastral setae on small protuberances (Figure 1), all setae situated behind level of apo.gla.

Lateral region. Exobothridial seta (ex) small but clearly discernible (Figure 3); two macropores situated one above and one below promontories of podocephalic canal (Figure 2 surrounding a.o.g). Opening of podocephalic canal on large promontories (Figures 2, 3, 5). Tubercles of interlamellar setae more or less cylindrical (Figures 12, 15); setae ro inserted on tubercles (Figures 12, 14); notogastral border clearly discernible even after long preservation in lactic acid; sejugal depression deep, easily discernible.

Ventral region. Specimens with cerotegument: plate-like cerotegumental structures on epimeres resulting in irregular levels on upper surface, epimeral furrows easily discernible with mus, cau and amorphous cerotegumental layer (Figure 25). Flat lateral cerotegumental zones, deep epimeral furrows 1 and 2. Epimeres III, IV small, epimeral setal formula (3-1-2-2). Seven pairs of genital setae in a single longitudinal line; aggenital setae not detected; three pairs of adanal setae; two pairs of anal setae.

Gnathosoma. Subcapitulum suctorial with short tube. Subcapitular setae large, especially a, m (Figure 25).

Legs (Table 1). Legs differ from those of congeners studied by the authors (See Table 1), particularities illustrated on SEM micrographs (Figures 34-42). Setal and solenidial formulae (trochanter to tarsus): I(1-6-4-5-19-1) (1-2-2); II(1-4-5-6-12-1) (1-1-2); III(2-3-3-4-11-1) (1-1-0); IV(1-3-4-5-10-1) (0-1-0).

Scalps. Exuviae of immature stases adhering one on top of the other, creating a multilayered structure. Each scalp extending anteriorly into a medial band (m.b) (Figures 14, 20, 23, 31) covering central zone, adhering to prodorsal surface (Figure 20) and extending backward towards ro setal insertion (Figure 20). Sometimes m.b is slightly detached (Figure 14).

Cerotegumental layer: medial band covered by thick amorphous layer with a network of round to polygonal depressions (Figure 13). Nymphal scalps with dentate peripheral ridge (p.d.r) (Figures 6, 8, 14, 20, 22, 23). Setae hardly discernible, scalps simple without anterior tuft of filaments. Larval scalp unlike the others, broad and elevated, Chinese hat-shaped, with three gibbose areas (gi) separated by transverse furrows (t.f) (Figure 22). In lateral view insertion of dp setae clearly visible (Indicated by Figure 22).

Remarks.

SEM is vital in order to observe aspects such as: 1) dorsal seta d associated with solenidium hardly discernible (detailed drawings are included to facilitate understanding) 2) clavate shape of small solenidia is problematic, as doubt regarding the exact shape remains if using only optical microscopy 3) the position of dorsal seta d relative to j1 and j2 on tibia II differs from Solenozetes makokouensis and Malgachebates peyrierasi . Changed angles of observation and rotation of specimens in SEM clarified the situation. 4) accessories available in SEM facilitated measurements of minute triangular scales of the sensillus with great precision 5) protuberances situated around the opening of the lateral gland also had to be observed from different angles. See Discussion for comparison with congeners.