Sadocepheus Aoki, 1965

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 : 64-65

Sadocepheus Aoki, 1965

Sadocepheus Aoki, 1965, p. 4 .

Type species: Sadocepheus undulatus Aoki, 1965

Diagnosis. The following diagnosis is modified from those of Luxton (1988a) and Ermilov and Corpuz-Raros (2017).

Small to large oribatid mites (390–900 μm); rostrum rounded; free lamellar cusps about one-quarter of length of lamellae, frequently projecting beyond rostrum, not fused with rostrum, with or without translamella; lamellar setae emerging from anterior margin of cusps, sometimes flanked by two small, sharp teeth. Bothridia fused with lamellae, projecting laterally. Posterior margin of prodorsum lacking condyles of enantiophyses H and B. Humeral process elongated, with reticulations and striae, originating from lateral margin at widest part of notogaster, with several undulating lobes and trapezoid anterior lobe with broad, pointed apex not reaching beyond bothridia. Concave curve formed between apex of anterior lobe of each humeral process and dorsosejugal scissure. Notogaster ovoid; with nine pairs of marginal or sub-marginal setae emerging from alveoli or tubercles ( S. foveolatus ). Epimeral plates II short, narrow. Pedotectum I prominent, often expanded laterally with large, curved spine; pd II large, square, trapezoid or lobed; discidium spine-like or lobed. Genital setae six pairs, shorter than width of genital plate, aligned longitudinally, aggenital setae one pair, anal setae two pairs, adanal setae three pairs; enantiophyses E4 and perigenital carinae absent; posterior margin of hysterosoma lacking mounds; chelicerae chelate-dentate, of normal proportions.

Remarks. Aoki (1965) defined Sadocepheus as having a smooth, rounded notogaster; broad, rugose lamellae and a translamella; six pairs of genital setae and five pairs of notogastral setae, later modified to six pairs ( Fujita and Fujikawa, 1986, p. 12), referring to the l and h series, i.e. with nine pairs including the p series.

Compactozetes serratus J. Balogh, 1970 was newly combined to Sadocepheus by Subías (2020) in the 15 th online update of his list of oribatids of the world. It is important to note this was a taxonomic opinion, not a nomenclatorial act, so is not covered under the International Code of Zoological Nomenclature or the 2012 amendment on electronic publication ( International Commission on Zoological Nomenclature, 2012). Subias (2020) is free to propose a new combination in his electronic catalogue and I agree with his opinion. Sadocepheus serratus has free lamellar cusps; they are not fused anteriorly with each other or with the rostrum and this character state differentiates Sadocepheus from Compactozetes which has fused cusps and paired, lateral prodorsal foramina.

In S. foveolatus Luxton, 1988b , S. makarcevae Sitnikova 1975 , S. nortonroyi Ermilov, 2020a , S. remus sp. nov., S. sausai Ermilov and Kalúz, 2021 , S. serratus , S. tohokuensis Fujikawa, 2003 , S. yakuensis Aoki, 2006 and S. undulatus the lamellae are broad, and more-or-less parallel and with a free cusp which is straight and transverse apically and may be indented where the lamellar setae emerge. In S. dubius Hammer, 1979 , S. tohokuensis Fujikawa, 2003 , S. subniger ( Ewing, 1917) and S. dhatiwalalensis Ermilov & Rybalov, 2019 the anterior lamellar cusp is in the form of a convex curve rather than a straight, transverse margin and the lamellae are not parallel but strongly convergent apically. In S. elevatus Mahunka, 1987 and S. donvictorianoensis Ermilov & Corpuz-Raros, 2017 the lamellae are strongly convergent and the cusps have indentations where the lamellar setae emerge.

In their definition of Sadocepheus, Ermilov and Corpuz-Raros (2017) state there are nine or ten pairs of notogastral setae. Of the 14 species in the genus described to date, all have nine pairs, except for S. dubius and S. subniger ( Ewing, 1917) in which the number cannot be determined from the descriptions. Ermilov and Corpuz-Raros (2017) described their new species, S. donvictorianoensis , as having ten pairs (p. 32) but only nine are illustrated. In the definition of Sadocepheus , these authors also stated there are six to nine pairs of genital setae (p. 29). I determined all species have six pairs except for S. subniger , for which the number is not stated or figured in the original description by Ewing (1917), though Woolley (1957) illustrated five pairs in his re-description. However, he comments the single specimen is ‘almost black’ (p. 116) and has a heavy cerotegument, so he may have missed a pair.