Sculpteremaeus, Behan-Pelletier & Ermilov, 2020

Behan-Pelletier, Valerie M. & Ermilov, Sergey G., 2020, Sculpteremaeus olszanowskii gen. nov., sp. nov. (Acari, Oribatida, Cymbaeremaeidae) from chaparral in California, USA, with a reassessment of Cymbaeremaeidae, Zootaxa 4790 (2), pp. 341-357 : 342-343

Genus Sculpteremaeus gen. nov.

Type species: Sculpteremaeus olszanowskii sp. nov.

Generic diagnosis. Adult. With character states of Cymbaeremaeidae ( Grandjean 1953; Behan-Pelletier 1988). Lamella located dorsolaterally on prodorsum, comparatively long and narrow, with small cusp lacking teeth. Tutorium simple, ridge-like. Notogaster with marginal tectum; anterior margin not covering opening of bothridium. Dorsosejugal scissure interrupted medially. Small area of notogaster, posterior of interrupted dorsosejugal scissure, without sculpturing, with same pigmentation as rest of notogaster. Ventral region tapered posteriorly. Genital and anal apertures narrowly separated.

Description. Integument: Surface sculptured, other than small area of notogaster posterior of interrupted dorsosejugal scissure. Prodorsum: Rostrum rounded. Lamella located dorsolaterally on prodorsum, comparatively long and narrow, with small cusp lacking teeth. Lamellar setae inserted anteroventrally on lamellar cusps. Translamella, prolamella, sublamella and sublamellar porose area absent. Tutorium simple, ridge-like. Bothridial seta short, globose. Bothridium cup-shaped, without notch. Dorsosejugal porose area, dorsophragmata and pleurophragmata absent. Notogaster: Without octotaxic system of porose organs. Dorsosejugal scissure interrupted medially. Notogaster with marginal tectum; anterior margin not covering opening of bothridium. Pteromorphs absent; small bulge present in humeral region anterior of lyrifissure ia. With strong topographic relief comprising relatively flat marginal zone and medial convexity extending from level of lyrifissure im posteriorly, tapering to nearly reach level of seta h 2. Ten pairs of notogastral setae, all in marginal zone. Lyrifissure im most centrodorsal sensory structure, positioned at juncture of marginal zone and central convexity. Gnathosoma: Subcapitulum diarthric. Mentum with tectum. Palp with setation 0-2-1-3-9(+ω). Solenidion of palptarsus bacilliform, free; eupathidium positioned on tu- bercle. Axillary saccule absent. Chelicera chelate-dentate, with two acuminate setae and tapered Trägårdh’s organ. Lateral podosomal and epimeral regions: Pedotectum I represented by lamina of medium size, completely covering acetabulum I. Pedotectum II biconvex in dorso-ventral aspect, triangular in lateral aspect, with anterior lamina covering about half of acetabulum II. Custodium, circumpedal carina and humeral porose areas absent. Discidium present. Epimeral setal formula (I-IV) 3-1-2-2. Anogenital region: Ventral region tapered posteriorly. Genital and anal apertures narrowly separated. Four pairs of genital, one pair of aggenital, two pairs of anal and three pairs of adanal setae present; ad 1 and ad 2 postanal, ad 3 closely lateral to anal aperture. Preanal organ hollow, cup-like. Legs: All pretarsi heterotridactylous. Tibia I with dorsodistal apophysis bearing solenidia; φ 1 distally, φ 2 medially on apophysis, posteromedial to φ 1. Tarsi, tibiae, femora and trochanters III, IV with porose areas. Juvenile instars: Unknown.

Etymology. The name Sculpteremaeus refers to the presence of sculpturing on the body + ‘ eremaeus ’, a common suffix for generic names in Cymbaeremaeidae .

Remarks. Adults of Sculpteremaeus gen. nov. are morphologically most similar to species of Ametroproctus , and specifically those included in the subgenus Ametroproctus (Ametroproctus) in the presence of short interlamellar setae; medially incomplete dorsosejugal scissure; small area of notogaster, posterior of interrupted dorsosejugal scissure, without sculpturing, with same or lighter pigmentation as rest of notogaster; 10 pairs of notogastral setae with centrodorsal region of notogaster glabrous; four pairs of genital setae; and genital and anal apertures closely adjacent. Adults differ from those of A. ( Ametroproctus ) species by having a thin lamella and small, separate lamellar cusps (versus well-developed lamella with large lamellar cusps, connected by translamella).

It is unclear whether the small circular area of notogaster, posterior of the interrupted dorsosejugal scissure, which lacks sculpturing, but has the same pigmentation as rest of notogaster is a true lenticulus, such as is found in Spineremaeus and Scapheremaeus ( Colloff 2011) . This area of Sculpteremaeus has the same morphology as that of Ametroproctus (A.) oresbios Higgins & Woolley, 1968 and A. (A.) tuberculosus Behan-Pelletier, 1987.

It is possible that with discovery of its immatures, Sculpteremaeus may be considered a subgenus of Ametroproctus . Behan-Pelletier (1987) placed Coropoculia in synonymy with Ametroproctus , and recognized 2 subgenera, on the basis of immatures, specifically the tritonymph of A. (A.) aridus Behan-Pelletier, 1987 , which shows character states that are expressed in species of Coropoculia.