Autogneta longilamellata ( Michael, 1885 )

Behan-Pelletier, Valerie M., 2015, Sexual dimorphism in Autogneta, with description of three new species from North America and new diagnosis of the genus (Acari, Oribatida, Autognetidae), Zootaxa 3946 (1), pp. 55-78 : 68-70

Autogneta longilamellata ( Michael, 1885)

Figs 31–36

Material Examined. Germany, South-West, near Offenburg, 48.393°N; 7.921°E, 3.xi.1993 (collected by Research Group Beck, Karlsruhe, Germany; personal correspondence G. Weigmann), 2 females, 4 males from tree stump, beech forest. USA: Virginia, Grayson Co., Hwy 603 at Fox Creek, 6 km W. Troutdale, 36.696°N, 81.471°W, 6.viii.1986 (E. E. Lindquist), 2 females from Trametes versicolor polypore fungi and lichen on hardwood; Virginia, Blue Ridge Parkway, Washington National Forest, Wintergreen Trail, 37.930°N, 78.952°W, 1.x.1992 (V. Behan- Pelletier), 1 male from in and under decaying tree trunk in oak-hemlock forest; Alabama, De Kalb, Co., De Soto state Park, Rhododendron Trail, 34.501°N, 85.618°W, 27.ix.1992 (V. Behan-Pelletier), 3 females from moss at base of hemlock; Canada: Newfoundland, Gros Morne National Park, Western Brook Trail, 20 mi N Rocky Harbour, 49.649°N, 57.755°W 14.viii.1976 (E. E. Lindquist), 2 females from small Polyporus on fir trunk; Pasadena, 49.009°N, 57.628°W, 30.vii.1976 (E. E. Lindquist), 1 male from under bark on dead birch limb; Nova Scotia, Cape Breton Highlands National Park, Fishing Cove Trail, 46.674°N, 60.958°W, 27.viii.1984 (V. Behan- Pelletier), 7 females, 5 males from bract and soft fungus on fallen maple; New Brunswick, 2–29.v.1968 (D.P. Pielou), 12 females, 4 males from Polyporus betulinus ; Kent Co., Kouchibouguac National Park, 46.850°N 64.967°W: 20.ix.1978 (S. J. Miller), 1 female, 1 male from polypore fungus; 21.vii.1978 (I. M. Smith), 4 females from bark and litter at base of dead red oak; 7–19.vii.1977 (I. M. Smith), 1 male from ant nest in log; mixed woods beside meadow at La Source Picnic area, 10–16.vii.1977 (I. M. Smith) 1 male from decaying spruce log, 1 male from white spruce duff; 23.vii.1978 (I. M. Smith), 4 females from Fuligo septica on white pine log; 27–29.ix.1977 (I. M. Smith), 1 male from ant workings and soil under fir log; 15.vi.1978 (R. Cope), 1 female, 1 male from moose dung in mixed woods; temporary pond area, 10.viii.1977 (E. E. Lindquist), 1 female from polypore fungi on fir stump; Québec, Gaspésie Provincial Park, Mont Albert trail, 48.957°N, 66.020°W, 29.vii.1981 (E. E. Lindquist), 1 female from bracket fungus on spruce; Gatineau Park, 45.583°N 76°W, 6–9.v.1968 (D.P. Pielou), 2 males from Populus betulinus ; Ontario: St. Lawrence Island National Park, Thwartway Island, 44.298°N, 76.180°W, 9.xi.1976 (E. E. Lindquist and I. M. Smith), 1 male from bark of white pine log infected with Ips; Eganville, Shaw Woods Nature Reserve, 45.667°N, 77.267°W, 20.v.1993 (B. Eamer), 1 female from secondary forest; S. shore Black Sturgeon Lake, 49.358°N 88.881°W, 23.viii.1972 (E. E. Lindquist), 1 female, 1 male from Polyporus betulinus on dead birch limbs; Algonquin Park, 45.8°N, 78.7°W, 29.viii.1966 (D.P. Pielou), 1 male from Polyporus betulinus .

Diagnosis. Adult. Apophyses posteriorly on prodorsum expressed as 1 pair of discrete U-shaped tubercles overhanging dorsosejugal scissure. Bothridial seta 41–53, clavate, head (about 23) smooth proximally, with minute spicules distally. Notogastral setae thick, barbed, tapered. Genital setae 6 pairs. Femur I without tubercles in proximal third of leg. Genua I and II with seta v’ present. Male dimorphism expressed as long, narrow porose area (ca. 176 long, 7–10 wide) positioned transversely between setae h3–h3, not bearing either setae h1 or p1. Mutual distance of setae p1–p1 similar in male and female (28–38).

FIGURES 31–36. Autogneta longilamellata (Michael) . Differential interference contrast microscope images of adults: 31, female, prodorsum and anterior of notogaster, with arrow to posterior apophysis on prodorsum (5 layers combined); 32, female, notogaster (5 layers combined); 33, female, posterior of notogaster, showing absence of porose region; 34, male, posterior of notogaster, showing porose region mediad and laterad of setae p1; 35, male, posterior of notogaster, showing porose region extending to and anterior of lyrifissure ih; 36, male, posterior of coxisternum, white arrow to undulating surface ridges of border of epimere IV, black arrow to cluster of tubercles posterior of acetabulum IV. Scale bar: 31–34 = 25, 35 = 10, 36 = 20.

Additional Observations. Adult. Dimensions (based on 12 specimens from Nova Scotia, Cape Breton Highlands National Park, Canada). Total length: females (n = 10) 312 (298–336); males (n = 10) 295 (range 278– 307). Notogastral length: females (n = 9) 184 (168–192); males (n = 10) 173 (range 163–187).

Prodorsum: (Based on specimens from eastern North America and Germany). Rostral incision 11–16. Costula 78–82, medial and lateral edges undulating; bearing seta le anteriorly. Enantiophysis E well developed lateral to proximal third of costula. Rostral seta thin, weakly barbed, acuminate; lamellar, interlamellar and exobothridial setae thicker than rostral seta, weakly barbed, tapered; ro 21–28, le 24–29, in about 25, ex about 11. Mutual distance ro–ro about 16, le–le 18–21, in–in about 35. Humeral enantiophysis well-developed (Fig. 31).

Notogaster: With U-shaped furrow well-developed, outlined by microtubercles. Notogastral setae subequal in both sexes, thick, weakly barbed (Fig. 32), tapered, 23–34 long with c shortest, 23–26. Setae p1 and h1 not positioned in transverse alignment, not positioned on porose area. Dimorphism expressed as long, narrow porose area (ca. 176 long, 7–10 wide) in male positioned transversely between setae h3–h3, not bearing either setae h1 or p 1 in male. Mutual distance of setae p1–p 1 in male and female similar (28–38).

Ventral Region: Posterior margin of epimere IV outlined by undulating ridges laterally and small foveae medially (Fig. 36). Circular patch of tubercles posterior to acetabulum IV (Fig. 36, black arrow).

Remarks. Both males and females of this species are easily recognized by the combination of 1 pair of discrete U-shaped tubercles overhanging the dorsosejugal scissure, posterior of epimere IV outlined by undulating ridges, and the strong, tapered notogastral setae. Sexual dimorphism in this species consists of males with long, narrow porose area, ca. 176 long and 7–10 wide, extending between level of setae h3–h3, not bearing either of setae h1 and p1.

Grandjean (1963) compared type material of A. longilamellata from Great Britain with his specimens, collected in the region of Paris, Strasbourg and Mongaillard, and considered them conspecific. Hull (1916) listed his A. longilamellata specimens as coming from Epping Forest, southeast England and from Cheshire and Scotland; we do not know which specimens Grandjean used for comparison. Grandjean (1963) noted small variation in the illustrated position of rostral setae in Swedish specimens of Autogneta longilamellata (posterior of rostral incision) (illustrated in Forsslund (1947)) from specimens he examined from France (level of base of rostral incision); specimens from eastern North America have a similar position of rostral setae to French specimens.

In addition to describing immatures of this species, Grandjean (1963) expanded on the description of the adult, noting the large range in adult length (295–350) and differences in character states from A. penicillum , Conchogneta dalecarlica and Rhaphigneta numidiana . He noted no evidence of sexual dimorphism in seta a’ on tarsus I of the male, which I confirm, but overlooked the weak porose region posteriorly on the male notogaster (Figs 34, 35).

Grandjean (1963) noted that A. longilamellata is the most common autognetid in France at lower elevations, and that its main habitat is rotting wood of stumps or fallen trunks in forests. Similarly, many specimens from eastern North America have been collected from these microhabitats and from bracket fungi (see Material Examined above). This species is among many considered characteristic of deadwood by Sokołowska et al. (2009). In their study of Oribatida of 11 habitats ranging from forest to grassland to seashore, Penttinen et al. (2008) found Autogneta longilamellata to be associated only with decaying wood and Skubała & Duras (2008) and Skubała and Maślak (2010) found this species primarily associated with early stages of decay in fallen spruce logs, that is, logs still with their cover of bark. Huhta et al. (2012) found this species to be associated only with tree trunk and stumps among the microhabitats they examined. This species has also been recorded from the sporocarps of Fomotopsis pinicola ( Maraun et al. 2014) . Although primarily associated with decaying wood, this species has also been recorded occasionally from general forest litter, e.g., Déchêne (2007) from forest litter in Québec, Canada, and Zaitsev & Berg (2001) found this species in a number of different forest localities in The Netherlands. It has also been found on young Scots pine trees affected by pollution ( Seniczak et al. 1997). Krivolutsky and Lebedeva (2004) found one specimen in feathers of a Jackdaw, and Lebedeva & Lebedev (2008) found this species in bird nests on the Murmansk Coast, Russia.