Oribatella plummeri Jacot, 1934

Behan-Pelletier, V. M., 2011, Oribatella (Acari, Oribatida, Oribatellidae) of eastern North America, Zootaxa 2973 (1), pp. 1-56 : 37-38

Oribatella plummeri Jacot, 1934

Oribatella brevicornuta plummeri Jacot, 1934, p. 709

Oribatella plummeri Jacot, 1934 ( Johnston 1965, p. 61)

( Fig. 19C, D )

Material examined. Cotypes: ( MCZ No. 30702 (2 females), 30703 (1 female), 30704 (1 female): USA, Maryland, Plummer’s Id, (H. S. Barber) from deep layer of old leaves ( MCZ); North Carolina, Buncombe Co., Bent Creek Experimental Forest , from A.P. Jacot Collection, slides 35F4.2-27 (2 females) and 35F4X-33 (17 specimens) ( RNC) .

Diagnosis. Total length of adult 405–455 µm. Integument of notogaster, ventral and anal plates micropunctate, coxisternal region with fine striae. Rostrum strongly projecting over gnathosoma, margin undulating, with or without pair of minute dens laterally. Lamella (including cusp) about 157 µm long, cusp 106–118 µm long, about 48–52 µm wide at level of insertion of seta le. Cusps contiguous or overlapping anteromedially; separated posteromedially, leaving prodorsum visible through oval opening, about 29 µm at greatest width ( Fig. 19D ). Medial and lateral dens on lamellar cusp subequal, about 48 µm long. Medial dens without teeth, lateral dens with 0–3 teeth on lateral margin, varying among specimens and on either side of same specimen. Lamellae without striae. Translamella without tooth, about 24 µm at greatest width, 17 µm deep ( Fig. 19D ). Setae ro about 89 µm long, strongly barbed along length, acuminate, strongly directly medially. Setae le about 74 µm long, thick, heavily barbed, tapered. Setae in 137–178 µm long, thick (less so than le), heavily barbed, tapered; mutual distance of pair about 87 µm. Bothridial setae about 121 µm long, barbed, similar in shape to seta le but more spindle-shaped. Exobothridial setae about 29 µm long, thin, barbed tapered. Genal tooth broad, subrectangular, with dens ventrodistally, with longitudinal ridge ventrally. Tutorium about 156 µm long, of which cusp about 84 µm long, rectangular, distal margin with 5 dens. Custodium about 53 µm long, tapered, extending anterior of pedotectum II, directed slightly anteromedially ( Fig. 19C ). Porose area Al about 10 µm in diameter. Notogastral length subequal to width. Anterior margin undulating, convex lateral of bothridium, with about 6 transverse ridges. Pteromorph with short ridges at anterior margin; with small dens on anteroventral margin. Four pairs of porose areas, Aa about 14 µm in diameter. Ten pairs of barbed, tapered notogastral setae present, about 62 µm long; lm posteromedial of Aa, lp anterior and slightly anteromedial of A1. Distance setae h 1 –h 1 about 43–50 µm, wider than distance p 1 –p 1, 24–29 µm. Small U-shaped lenticulus present. Coxisternum with longitudinal striae. Epimeral setae mostly 22 µm long, weakly barbed, except 3c 58 µm long, subequal in shape and width to other epimeral setae. Genital, aggenital, anal and adanal setae weakly barbed, about 21 µm long. Genital setae 1+5, 1 pair of genital setae on anterior margin of genital plates. Postanal porose area oval, 17 µm long. Mentum with transverse carina anteriorly, with short tectum. Axillary saccule about 4 x 2 µm. Leg setation (I to IV): trochanters, 1-1-2-1; femora, 5-5-2-2; genua, 3(1)-3(1)-1(1)-2; tibiae 4(2)-4(1)-3(1)-3(1); tarsi, 20(2)-15(2)-15-12. Seta l” of genu I about 31 µm. Tarsi monodactylous.

Remarks. Lateral dens of lamellar cusps lacked teeth on all cotype specimens, but up to 3 were present on non-type specimens.

Oribatella plummeri was first proposed as a subspecies of O. brevicornuta by Jacot (1934), and subsequently given species status by Johnston (1965). It is clearly distinguishable from O. brevicornuta by the width of the oval opening between lamellar cusps being about 29 µm (17-19 µm in O. brevicornuta ), and the monodactylous tarsi (tridactylous in O. brevicornuta ).

Distribution and Ecology. This species is known only from Maryland and North Carolina.

Figures

FIGURE 19. A–E Oribatella nortoni sp. nov., O. plummeri Jacot, and O. pusilla Berlese, differential interference contrast microscope images of adult: A, B, Oribatella nortoni, A, detail of lamellae; B, detail of tutorium with 2 dens; C, D, O. plummeri, C, dorsal aspect of type female; D, custodium (6 layers combined); E, O. pusilla, prodorsum of topotype female, with arrow to lamellar bridge. Scale bars: A, B, D, E = 50 µm; C = 25 µm.