Oribatella heatherae, Behan-Pelletier & Walter, 2012

Behan-Pelletier, Valerie M. & Walter, David E., 2012, 3432, Zootaxa 3432, pp. 1-62 : 19-23

Oribatella heatherae sp. nov.

( Figs. 8, 9, 10A–C, 28C, 30C)

Material examined. Holotype: adult female. Canada: Alberta, Kananaskis Country, Fortress Mt., 12.vii.1983 ( VBP) from moss and lichens among rocks on alpine scree slope; deposited in the CNC, type number 24039. Paratypes: 10 males, 9 females with same data as holotype; Alberta, Cypress Hills Provincial Park, Firetower area plateau, 3 mi S Elkwater, 20–27.vii.1978 ( EEL) 1 female from old cow manure (with scarabeid larvae); same data except, Lodgepole Pine Campground area, 2 male, 1 female from moss and rotten wood; 4 females, 1 male from rotten stump with some moss; 1 female from liverwort mat; 1 male from vertical moss mat and substrate on mineral soil; Waterton Lakes National Park, Alderson-Carthew Trail, 2347m, 18.vii.1986 ( VBP) 2 males from litter under Potentilla , Dryas , moss, lichens, Carex ; 2 males, 2 females from litter under Smelowskia , Erigeron, Silene and moss among shale. Paratypes deposited in the CNC, PMAE. IZ, RNC and USNM.

Diagnosis. Mean total length 500–574 µm. Rostrum with distinct medial crest dorsally; rostral margin flattened, with minute dens laterally. Translamella without tooth. Medial dens on lamellar cusp thickened, narrow, nearly isodiametric (71–75 µm long); lateral dens 57–62 µm long, shorter than and 2 to 3 times width of medial dens. Area defined by medial and lateral dens subrectangular. Bothridial setae 112–123 µm long, with barbed, fusiform head, tapered distally. Epimeral setae barbed, with 3c longest seta, 56 µm; 4c weakly barbed, about 12 µm long, subequal in shape and length to seta 1a. Custodium 43–65 µm long, tapered. Ten pairs of weakly barbed notogastral setae 33–62 µm long, seta lm posteriad Aa, and lp anterior A1. Notogastral porose areas with deep pore canals. Distance setae h 1 –h 1 35–41 µm, greater than distance p 1 –p 1 29–32 µm. Tarsi heterotridactylous.

Description. Adults. Dimensions: Mean total length: female (n = 10) 549 µm (range 525–574); male (n = 10) 523 µm (range 500–554). Mean notogastral width: female (n =10) 365 µm (range 347–380); male (n =7) 346 µm (range 337–350).

Integument: Integument of prodorsum, notogaster, anal plate, ventral plate micropunctate. Integument of rostrum, tutorium, pedotectum I, genital plate with deep puncta outlined by striae.

Prodorsum: Rostrum with distinct medial crest ( Fig. 10B); rostral margin flattened with minute dens laterally. Lamella 172–177 µm long, of which cusp 135–143 µm long, almost parallel; about 63 µm wide at level of insertion of seta le. Lamellar cusps diverging anteromedially and posteromedially, prodorsum visible through oval opening, about 8 µm wide; translamella without tooth, about 10 µm at greatest width, 5 µm in depth ( Figs 8, 10A). Medial dens on lamellar cusp thickened, narrow, nearly isodiametric (71–75 µm long); lateral dens 57–62 µm long, shorter than and 2 to 3 times width of medial dens, with 2–4 teeth on lateral margin. Area defined by medial and lateral dens subrectangular ( Figs 8, 10A). Number of teeth on lateral margin of dens varying among specimens and on either side of same specimen. Seta ro about 110 µm long, strongly barbed along length, acuminate, curved anteromedially. Seta le 108–123 µm long, thick, heavily barbed, tapered. Seta in 172–194 µm long, thick (less so than le), heavily barbed, parallel; mutual distance of pair 77–80 µm. Bothridial setae 112–123 µm long, with barbed, fusiform head, tapered distally ( Figs 8, 10A), stalk long, smooth; head directed slightly anterodorsally. Exobothridial seta about 25 µm long, thin, tapered.

Lateral region of podosoma: Genal tooth broad, subrectangular, with dens ventrodistally, with longitudinal ridge basally. Tutorium with cusp 195–208 µm long, extending anterior of rostrum, of which cusp 114–135 µm long, rectangular, slightly convex ventrally, distal margin with 7–11 teeth ( Fig. 10B). Custodium 43–65 µm long, tapered ( Fig. 28C). Porose area Al about 10 µm in diameter.

Notogaster: Length subequal to width. Anterior margin undulating, convex region lateral of bothridium with 5–9 transverse ridges. Pteromorph with short ridges at anterior margin; anteroventral margin minutely serrate. Octotaxic system in form of four pairs of porose areas, with deep pore canals ( Fig. 30C), Aa about 11 µm. Ten pairs of long, curved, weakly barbed notogastral setae present (33–62 µm long) c seta longest, seta lm posteriad Aa, and lp anteriad A1 ( Fig. 8). Distance setae h 1 –h 1 35–41 µm, greater than distance p 1 –p 1 29–32 µm. Lenticulus broadly subtriangular in outline.

Ventral Region: Epimeral setae 12–56 µm long, barbed, with 3c longest seta; 4c weakly barbed, about 12 µm long, subequal in shape and length to seta 1a ( Fig. 28C). Genital, aggenital, anal and adanal setae finely barbed, about 8–10 µm long. Genital setae positioned in a curve on genital plate, 1+5. Postanal porose area oval, 26x12 µm.

Gnathosoma : Anterior border of mentum with thickened transverse, reflexed ridge, without tectum. Axillary saccule about 5 x 2 µm.

Legs. Setation (I to IV): trochanters, 1-1-2-1; femora, 5-5-3-2; 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 genua I and II about 47 and 45 µm, respectively; l” of tibiae I and II about 37 and 41 µm, respectively. Tarsi heterotridactylous.

Tritonymph. Dimensions: Mean length: tritonymph (n = 3) 522 µm (515–525).

Integument: Weakly sclerotized and faintly micropunctate, except for pair of indentations at posterior of prodorsum; sclerotization encompassing all of gastronotal region, ventral region anterior to level of cupule iad, adanal and anal plates and lateral of coxisternal region.

Prodorsum: Setae ro, le, in and ex barbed, tapered, about 93–101, 147, 183 and 143 µm long, respectively. Mutual distance of setae ro about 16 µm, of setae le about 18 µm and of setae in about 56 µm. Seta ex directed laterally, other prodorsal setae directed anteriorly or anterolaterally ( Fig. 9). Bothridial seta weakly barbed, tapered, blunt distally, about 126 µm long. Bothridium with ridges transecting posterior margin ( Fig. 9).

Gastronotic region: Margin carinate except anteriorly; outline slightly uneven, caused by weak swelling around setal tubercles ( Fig. 9). Setae barbed, tapered, with da slightly thinner than dm and dp ( Fig. 9). Setae c 1, c 2, da, dm, dp directed posteriorly; c 1 lying beneath scalps of previous instars (not illustrated). Setae c 3 la, lm, lp, h 3, h 2 directed posterolaterally. Setal lengths (in µm) approximate (due to some terminal breakage and difficulty in measurement): c 1 (109), c 2 (230), c 3 (177), da (153), dm (114), dp (145), la (190), lm (159), lp (159), h 1 (174), h 2 (164), h 3 (168), p 1 (100), p 2 (48), p 3 (38). Distance (in µm) da–da, dm–dm and dp–dp about 23, 63 and 155, respectively. Ventral surface of scalps with pair of setiform, sheathlike callosities, accommodating seta da of preceding instar; sheaths browner, more sclerotized than rest of scalp.

Ventral region: Epimeres sclerotized laterally. Epimeral setation 3-1-3-3; all thin, smooth, about 12 µm. Five pairs of genital setae, about 12 µm, aligned in longitudinal row. Aggenital seta about 12 µm. Three pairs of adanal setae barbed, about 20 µm; two pairs of anal setae weakly barbed, about 7 µm; cupule iad present. Axillary saccule present, about 4 x 2 µm.

Legs: Seta l” of femur, genu and tibia I, II and l’ of genu III very broad, barbed, spinous, almost blunt distally.

Other instars: Only known from scalps (1 specimen). Hysterosomal setae similar to those of tritonymph in form and proportions.

Etymology. This species is named in honour of our friend, colleague, partner (to DEW) in collecting Oribatida and eminent expert on Acari, Dr. Heather C. Proctor.

Remarks. In Alberta this species can easily be mistaken for O. yukonensis , described below. Both species are large, and have a similar habitus. They differ mainly in: the shape of the lamellar cusps, with a subrectangular shaped indentation in O. heatherae vs. a triangular indentation in O. yukonensis ; in the integument of pedotectum I, with short ridges in O. yukonensis , without ridges in O. heatherae (compare figures 10C and 10E); and in dimensions of various characters, with O. heatherae the slightly larger species. We initially questioned the distinctness of these two species, but the hysterosomal setae of the larva clearly argue against conspecificity. Those of larval O. heatherae are similar in shape to those of the tritonymph (based on scalps borne by tritonymph), whereas setae c 1, da, dm, dp of larval O. yukonensis are broadly expanded. This species is also similar in habitus to O. transtriata Behan-Pelletier, 2011 described from northeastern Canada ( Behan-Pelletier 2011). Oribatella heatherae differs in overall size (500–574 µm vs. 450–452 µm in O. transtriata ) and the shape of the lamellar cusp (a distinctly triangular indentation with le medially positioned in O. transtriata and distinctly subrectangular indentation with le more laterally positioned in O. heatherae ). Porose areas of the octotaxic system are larger in O. heatherae (about 11 µm vs. about 8 µm in O. transtriata ). Immatures of O. transtriata are not known. Eventually, these species may prove to be conspecific, but the high species diversity in other brachypyline taxa, e.g., Ceratozetes ( Behan-Pelletier & Eamer 2009) , and Eremaeidae ( Behan-Pelletier 1993) , from this biological rich region of western North America argue for caution.

Distribution and Ecology. This species is known from dry habitats at elevation in western Alberta.