Roynortonia, Ermilov, 2011

Ermilov, S. G., 2011, A New Genus And Species Of Amerobelbidae (Acari: Oribatida) From Vietnam, Acarologia 51 (3), pp. 275-282 : 275-276

Genus Roynortonia n. gen.

Diagnosis

General characters of the family Amerobelbidae ( Grandjean 1965) . Rostrum rounded in dorsal view. Lamellar lines absent. Rostral (ro) and lamellar (le) setae setiform, short. Interlamellar (in) setae setiform, long. Lamellar setae inserted closer to interlamellar setae than to rostral setae. Sensilli (ss) with short cilia. Bothridia modified, with long, rigid projection posteriorly. Dorsosejugal scissure complete, slightly convex. Notogaster with one pair of short, thin spines anterolaterally. Epimeral setal formula 3-1-3-3. Aggenital neotrichy absent, one pair of aggenital setae present. Epimeral setae 3b modified, long, thorn-like. Epimeral setae 3b, 3c, 4b and 4c positioned adjacent to each other, so that epimeres III and IV without setae laterally.

Type species — Roynortonia vietnamica n. sp.

Etymology — The genus is named in honor of Prof. Dr. Roy A. Norton (State University of New York, College of Environmental Science and Forestry, Syracuse, USA), the distinguished acarologist, for his extensive contributions to our knowledge of the oribatid mites.

Remarks — The family Amerobelbidae comprises five genera: Amerobelba Berlese, 1908 , Berndamerus Mahunka, 1977 , Hellenamerus Mahunka, 1974 , Mongaillardia Grandjean, 1961 , Rastellobata Grandjean, 1961 . Two other genera, Y ambaramerus and Grypoceramerus , have been included in Amerobelbidae , but I question this placement.

Aoki (1996) described Yambaramerus including it in Amerobelbidae . However both known representative of Yambaramerus , Y. arcuatus Aoki and Yamamoto, 2000 and Y. itoi Aoki, 1996 , differ from other Amerobelbidae by body proportions (prodorsum and notogaster approximately equal in length in Yambaramerus ; prodorsum obviously shorter than notogaster in other Amerobelbidae ), lamellar setae inserted on well-developed apophyses, close to each other (not inserted on well-developed apophyses, and not close each other in other Amerobelbidae ), lamellar lines well-developed (lamellar lines absent or slightly developed in other Amerobelbidae ), presence of ring-like structures adjacent to interlamellar setae (absent in other Amerobelbidae ), notogaster with two pairs of long and strongly developed thorn-like processes in humeral region (thorn-like structures absent or only one pair of small tubercles or spines present in other Amerobelbidae ).

Suzuki and Aoki (1970) described Grypoceramerus and included it in Amerobelbidae . However, the representative of Grypoceramerus , G. acutus Suzuki and Aoki, 1970 , strongly differs from other Amerobelbidae by body proportions (prodorsum and notogaster approximately equal in length in Grypoceramerus ; prodorsum obviously shorter than notogaster in other Amerobelbidae ), notogastral setae c and la adjacent to each other and separated from other setae (not adjacent to each other or removed from other setae in other Amerobelbidae ).

In my opinion, based on these character states Yambaramerus and Grypoceramerus are dissimilar to other genera of Amerobelbidae , and should not be considered members of this family. I do not discuss a place of Yambaramerus and Grypoceramerus in Ameroidea herein, their placement should be addressed in a separate publication.

Roynortonia n. gen. clearly differs from all other genera of Amerobelbidae by the following characters: 1) epimeral setae 3b modified, long, thorn-like, 2) epimeral setae 3b, 3c, 4b and 4c positioned adjacent to each other, 3) absence of aggenital neotrichy. Modified epimeral seta 3b is unique in Ameroidea and as far as I know it is unknown in Brachypylina. The presence of one pair of aggenital setae is unique in Amerobelbidae , all other genera express aggenital neotrichy; the type species of the new genus has an unusual structure – a long, rigid projection posterior to the bothridium. This is the first record of a bothridia bearing projection in Brachypylina. However, there are a small number of oribatid species with short bothridial projections in a same position in the Ameroidea, for example, Staurobates schusteri Grandjean, 1966 and Stauroma cephalotum Grandjean, 1966 in Staurobatidae .

The new genus is most similar to Amerobelba in morphology of lamellar setae, absence of lamellar lines, absence of well-developed notogastral tubercles in humeral region (absent in Amerobelba , only very short spines developed in Roynortonia n. gen.), position of notogastral setae.