Pterozetidae Luxton, 1988

Colloff, Matthew J., 2023, The oribatid mite superfamily Eutegaeoidea (Acari, Oribatida), with descriptions of new taxa from Australia and New Caledonia and a re-assessment of genera and families, Zootaxa 5365 (1), pp. 1-93 : 68-69

Pterozetidae Luxton, 1988

Pterozetidae Luxton, 1988a, p. 83 .

Type genus: Pterozetes Hammer, 1966, p. 78 .

Diagnosis. The following diagnosis is based on that of Luxton (1988a), modified to accommodate the transfer of Porrhotegaeus to Porrhotegaeidae fam. nov. (cf. below).

Lamellae long, well developed, fused with each other apically, their anterior margin concave and curved or Vshaped, with lateral points, but anterior margin not folded ventrally and fused with rostrum. Bothridia fused with bases of lamellae and prodorsum. With long, blade-like humeral processes extending from lateral margin at widest part of notogaster to point at least level with mid-length of lamellae, reflexed ventrally ( Dudichella ), but lacking marginal lobes posterior of main anterior lobe. Interlamellar setae present ( Pterozetes novazealandicus Hammer, 1966 ) or absent. Notogaster U-shaped, with eight or nine pairs of short, thin, smooth setae; those of l and h series positioned marginally. Pedotectum I large, broad, sub-rectangular in ventral outline; pd II rectangular or pointed; discidium sub-rectangular or ovoid. Anterior margin of pedotectum I and epimere I forming straight or curved transverse tectum covering posterior mentum. Perigenital carinae present ( Dudichella ) or absent ( Pterozetes ). Enantiophysis E4 present as posterior tubercle only ( Pterozetes lawrencei sp. nov.) or absent ( Dudichella and Pterozetes novazealandicus ). Six pairs of genital setae: aligned longitudinally in Pterozetes or with g 2 and g 5 displaced laterally in Dudichella . Three pairs of adanal setae. Anal plates lozenge-shaped.

Remarks. Norton and Behan-Pelletier (2009) considered Pterozetidae a junior synonym of Eutegaeidae due to the apparent lack of diagnostic characters at the family-level. However, the humeral processes of Pterozetidae originate on the lateral margin of the notogaster at its widest part, well posterior of the dorsosejugal scissure, and are curved and convex along their external margins, forming triangular, blade-like structures extending almost to the rostrum, covering most or all of legs I and II, and quite different from those of the Eutegaeidae . In her definition of Pterozetes, Hammer (1966, p. 78) pointed out that the humeral process ‘is different from that of Eutegaeus ’, in that it is more like a pteromorph than the cuticular projection from the anterior margin of the notogaster found in the latter genus. In Dudichella , the ventrally curved median margins of the humeral processes overlap with the lateral margins of epimeres I and II, which are broadened and excavated, covering legs I and II (J. Balogh, 1970).

The main character state that differentiates Pterozetidae from other families of Eutegaeoidea is that the anterior parts of the lamellae are fused with each other and their anterior margin is concave and curved or V-shaped, but is not folded ventrally and fused with the rostrum and with lateral foramina as in Compactozetes . Luxton (1988a, pp. 84, 85) considered the lamellar cusps of Dudichella are free and not fused, but J. Balogh (1970b, p. 36) described them as ‘medially confluent and thus X-shaped’ and his Fig. 1 clearly shows the cusps as fused in the midline, with a deep V-shaped indentation between the lateral apices. This arrangement is completely different from the free lamellar cusps of the Eutegaeidae , Neoeutegaeidae and Porrhotegaeidae fam. nov. I consider the morphology of the anterior margin of the lamellae a synapomorphy of Pterozetidae .

Pterozetidae is morphologically most similar to Compactozetidae in that the margins of the bothridia are fused with the prodorsum and bases of lamellae and the humeral processes originate on the margin of the notogaster at its widest part. However, they differ from those of the Compactozetidae in lacking the 2-4 lobes posterior of the apical humeral projection. As mentioned above, the lamellae of Pterozetidae are quite different in morphology from those of Compactozetes . Also, the anal plates of Pterozetidae are lozenge-shaped while those of Compactozetidae are rectangular.

Additional diagnostic characters for Pterozetidae are that epimeres I and II are very broad and long, whereas epimeres III and IV are much narrower and shorter. Pedotectum I is very large with sub-rectangular lateral margins, with an anterolateral point in Dudichella , and extend to the medial margin of the humeral process ( Pterozetes ) or overlap it ( Dudichella ). The anterior margin of pedotectum I and epimere I forms a straight or curved transverse tectum covering the posterior part of the mentum and the ventro-lateral margins of the gnathosoma, as in most Compactozetidae , but this structure is not present in the Eutegaeidae or Neoeutegaeidae . I consider there are sufficient character states of diagnostic value to retain Pterozetidae as a valid family. The interlamellar setae are absent in Pterozetes lawrencei sp. nov. and Dudichella but present in Pterozetes novazealandicus Hammer, 1966 (cf. Luxton, 1988c, Fig. 1A therein).

In Dudichella the lamellar setae emerge from the ventral surface of the lamellae, as in Porrhotegaeus (cf. below). Dudichella also differs from Pterozetes in having what J. Balogh (1970b) described as ‘minute, peloptoide’ [sic] chelicerae. It is unclear whether the chelicerae are truly pelopsiform (i.e. expanded basally) or are simply thin, attenuate and chelate-dentate as in Atalotegaeus mensarosi (cf. above).

Figures

FIGURE 1. Global distribution of genera and species of Eutegaeoidea and Cepheoidea, based on records of type localities of species described prior to the present work. Inset: detail of type localities of species in New Zealand.