The oribatid mite genus Topalia in Australia (Oribatida: Nosybeidae) and the taxonomic status of related families and genera Author Colloff, Matthew J. text Zootaxa 2019 2019-07-26 4647 1 290 321 journal article 25550 10.11646/zootaxa.4647.1.18 6446fee7-99f6-43cd-b37a-bb6ce3fade53 1175-5326 3353104 0A0CA1A2-046F-4D23-A7A9-02D2DB974D4D Topalia Balogh & Csiszar, 1963 Type species: Topalia problematica Balogh & Csiszar, 1963 , p. 477 , Figs. 27, 28. Diagnosis : With the following combination of character states: broad lamellae covering most of prodorsum; setae ro , le and in minute; ten pairs of minute notogastral setae; pedotectum I and II prominent. Subcapitulum narrow; chelicerae slim, sub-pelopsiform, dentate; Epimeral plates I trapezoid or sub-rectangular, much broader than long; epimeral plates III and IV sub-rectangular, separate or fused; considerably shorter/narrower than I and II . Discidium well-developed, pointed; enantiophysis E4 and perigenital carina present; with four pairs of genital setae. Tibia I with solenidion φ 1 lacking apophysis, or at most with a slight bulge; set back from the anterior margin of tibia. Tarsi monodactylous. Description : Non-poronotic brachypyline oribatid mites. Species with both males and females, though no indication of sexual dimorphism. With cerotegument of granular, reticulate and/or tuberculate microsculpture covering dorsal and ventral surfaces. Rostrum acute, entire or incised. Lamellae wide, covering most of prodorsum and bothridia ( Figs. 1a , 2a ); lamellar cusps extending anterior of rostrum, rounded apically, fused medially at base, with a short translamella; rostral, lamellar and interlamellar setae minute; lamellar setae positioned anterodorsally on cusp, with long insertion canal ( xx ). Bothridial seta club-shaped; stalk generally short; about as long as head ( Fig. 2e ). Bothridia with internal ring-like thickenings. Tutorium positioned ventral of lamellae, with or without cusp. Notogaster only slightly longer than wide, with rounded humeral projections and ten pairs of minute setae; c 1 , c 3 , da , dp and lm absent; dm in centrodorsal position, others marginal. Pedotectum I and II massive; pedotectum I covering acetabulum I, extending dorsally at least one-third of length of lamellae, pedotectum II triangular in lateral aspect, free end pointed and strongly curved dorsally. Discidium strongly developed between acetabula III and IV ; acutely pointed in ventral aspect. Subcapitulum narrow, about twice as long as broad; rutellum attenuated, with curved, sharp teeth; mentum without tectum ( Fig 6b ). Chelicera narrow, sub-pelopsiform, dentate, with opposing digits ( Fig. 2c ). Palp tarsus with seven setae; solenidion not on apophysis, separate from seta acm ( Fig. 2d ). Epimeral plates I trapezoid or sub-rectangular, much broader than long; epimeral plates II longer than broad; epimera III and IV sub-rectangular, much shorter than I and II , their lateral margins extending distance of about half length of epimeral plates II ( Fig. 3a ); epimeral setation typically 2-1-2-3 or 2-1-2-2. Enantiophysis E4 present; E2 and/or V occasionally present ( Fig. 4b ). Anteriorly-projecting condyle of E4 on apex of lath-like carina lateral of genital plate ( Fig. 1b , pc ). With four pairs of genital setae, posterior two pairs separated from anterior ones; one pair of aggenital setae between genital plate and lateral ridge; two pairs of anal setae on main body of anal plate, not on margin; two pairs of adanal setae ( Fig. 1b ). Anal and genital plates adjacent or close together, each surrounded by ring of sclerotised cuticle; anal and genital plates similar in shape: oval-to-sub-rectangular; anal plates never lozenge-shaped; lyrifissure iad present in para-anal position; ventral plate rounded caudally. With tectum on ventral plate at level of circumgastric scissure ( vpt ), visible in lateral view; gouttière de coaptation au notogaster ( tcn ) of Grandjean (1958 , p. 122). Legs lacking porose areas or saccules ( Figs. 3 , 8a ); seta d absent from genua I, II and tibiae I–III. Trochanters and femorae broadly ovoid, flattened and keeled ventrally; solenidia φ 1 and φ 2 on tibia I emerging from flat cuticular surface, not on prominent cylindrical apophyses. Tarsi long, slender, monodactylous. Remarks : Balogh & Csiszar (1963) defined Topalia as follows: “lamellae meeting in median line, wide, covering prodorsum and rostrum, lamellar and interlamellar setae very small. Tectopedium I very large, shell-shaped. Four pairs of genital setae. Legs monodactylous. Body with granulated cerotegument.” This definition, while adequate at the time, would now include the morphologically most similar genus Nosybea and, apart from it having five (rather than four) genital setae, Lamellocepheus . Further, the following species of Topalia have broad lamellae that do not meet in the midline: T. caliginosa sp. nov. , T. katyae sp. nov. , T. royi sp. nov. and T. velata . Mahunka (1993) distinguished Nosybea from Topalia based on the following character states: (1) notogaster with one unpaired median crest rather than 1–2 pairs of longitudinal crests; (2) notogaster with lateral excavations (cavernae) rather than unexcavated; (3) coxisternal region without opposite apophyses (i.e. enantiophysis E4 and associated perigenital carinae) and with 12 ring-shaped thickenings rather than with opposite apophyses but without ring-shaped thickenings; (4) epimeral setal formula of Nosybea 2-0-2-3 rather than 3-1-3-3 (which is not the formula for Topalia ; cf. above). This diagnosis requires modification in light of the current conception of Topalia because the presence of ring-shaped excavations on the coxisternite (epimeral foveolae) is shared by Topalia katyae sp. nov. (cf. below, Fig. 6b ). However, in this species, there are only two pairs, located medially between epimera I, II and III . In Nosybea genavensis some of the epimeral foveolae are not paired, there are twelve of them, and more heavily sclerotised than in T. katyae sp. nov. , and distributed over the entire epimeral region ( Fig. 12b ). Nevertheless, the narrow median notogastral carina of Nosybea is clearly differentiated from the broad, flat centrodorsal ridge of Topalia , as is the reduced epimeral setation of 2-0-2-3, the lateral cavernae and the absence of enantiophysis E4 and perigenital carinae. Additional characters that distinguish Nosybea from Topalia are: (1) bothridial seta asymmetrically dilated and with spicules, rather than club-shaped with blunt spines ( Figs. 10a, b ); (2) with pedotectum II divided by median carina (visible in lateral view), rather than entire; (3) 11 pairs of notogastral setae rather than ten: Nosybea retains seta lm , which is absent in Topalia ( Figs. 1a , 11a, b ).