Diamphidaxona

Smith, Ian M. & Cook, David R., 2006, North American species of Diamphidaxona (Acari: Hydrachnida: Hygrobatidae), Zootaxa 1279, pp. 1-44 : 15-18

Diamphidaxona (s. s.) pallida Cook

( Figs. 54–61 , 95–106 )

Diamphidaxona pallida Cook, 1963 , pp. 111­114, figs. 1, 4, 6, 7, 9, 10; male, female.

Description. Character states of Diamphidaxona (s. s.). Dorsal edge of camerostome acutely rounded anteriorly and not projecting beyond anterior end of idiosoma ( Figs. 56, 59 ). Pedipalps with tibia bearing one ventral seta and tarsus with ventral spine­like seta bearing two slightly curved denticles ventrally ( Figs. 57 , 98, 99, 100 ). Dorsal shield with anterior plate of same width as posterior plate and rounded anteriorly ( Figs. 54 , 95, 96 ). Ventral shield with suture lines between third and fourth coxal plates with medial loops deeply arched and lateral loops U­shaped and open anteriorly ( Figs. 56, 59 , 103, 104 ). Projections covering insertions of fourth pair of legs with anterior extensions long and directed anteriorly parallel to edges of ventral shield ( Figs. 56, 59 , 101, 102 ). Genital field of males fused with ventral shield ( Fig. 56 , 105 ). Measurements: Male (n=5): Length/ width anterior dorsal plate 149–168/252–267, length/width posterior dorsal plate 287–312/ 257–272, length/width ventral shield 446–495/304–317, length/width genital field 72–89/ 124–139. Lengths pedipalp segments: Tr 15–16, Fe 53–63, Ge 38–43, Ti 55–60, Ta 28–30. Lengths leg segments: ITr 38–40, IBFe 55–63, ITFe 53–60, IGe 60–68, ITi 63–70, ITa 75–80; IITr 35–41, IIBFe 53–58, IITFe 50–58, IIGe 58–65, IITi 60–63, IITa 70–75; IIITr 34–38, IIIBFe 50–55, IIITFe 48–53, IIIGe 58–65, IIITi 65–70, IIITa 73–78; IVTr 75–83, IVBFe 73–80, IVTFe 80–90, IVGe 95–100, IVTi 98–103, IVTa 94–100. Female (n=5): Length/width anterior dorsal plate 168–183/262–292, length/width posterior dorsal plate 302–322/267–292, length/width ventral shield 446–475/322–347, width genital field 124–139. Lengths pedipalp segments: Tr 15–18, Fe 60–65, Ge 41–45, Ti 60–63, Ta 30–33. Lengths leg segments: ITr 38–43, IBFe 60–65, ITFe 58–65, IGe 68–73, ITi 68–73, ITa 78–83; IITr 38–43, IIBFe 55–60, IITFe 55–60, IIGe 65–68, IITi 65–68, IITa 75–78; IIITr 35–40, IIIBFe 53–58, IIITFe 50–55, IIIGe 63–68, IIITi 65–73, IIITa 78–85; IVTr 80–88, IVBFe 78–85, IVTFe 90–95, IVGe 105, IVTi 103–108, IVTa 100–105.

Specimens examined. CANADA: New Brunswick: Charlotte Co.: Digdeguash River beside Hwy. 770, Rollingdam, 30 June 1989, IMS — 1 male, 3 females (slides, CNC). York Co. Nashwaak River beside Hwy. 8, 1.7 km north of Durham Bridge Road, 2 July 1968, IMS — 1 male, 3 females (slides, CNC). Nova Scotia: Halifax Co.: Musquodoboit River beside Hwy. 224, Middle Musquodoboit, 24 September 1984, IMS — 2 males, 5 females (slides, CNC). Inverness Co.: South West Margaree River beside Hwy. 395 north of Upper Margaree, 19 September 1984, IMS — 2 females (slides, CNC). Victoria Co.: North Branch of North Aspy River beside Cabot Trail just east of North Mountain, Cape Breton Highlands National Park, 8 July 1981, IMS — 1 male (slide, CNC). Clyburn Brook, Clyburn Brook Picnic Area, Cape Breton Highlands National Park, 16 July 1981, IMS — 2 females (slides, CNC). USA: Alabama: Lauderdale Co.: Stream beside Natchez Trace Parkway 7 km south of Tennessee state line, 5 October 1994, IMS — 3 males, 7 females (slides, CNC), 38 males, 45 females (GAW, CNC). Arkansas: Carroll Co.: Kings River beside Rt. 62, 21 July 1960, DRC — 4 paratype males, 3 paratype females (slides, CNC), 2 paratype females (GAW, CNC). Georgia: Murray Co.: Holly Creek beside Forest Road 18, 1.9 km beyond end of pavement east of Chatsworth, 29 September 1992, IMS — 1 female (slide, CNC). Indiana: Warren Co.: Stream beside Rt. 41, 4 miles (6.4 km) south of Attica, 12 July 1964, DRC — 2 males (slides, CNC); tributary of Wabash River beside Rt. 63, 5 miles north of Rt. 28, 13 October 1970, DRC — 1 female (slide, CNC). Kentucky: Adair Co.: Russell Creek beside Rt. 80, 5 miles (8 km) from Russell Springs, 14 July 1964, DRC — 1 male (slide, CNC). Maine: Piscataquis Co.: Trout Brook, Baxter State Park, 25 July 1980, IMS — 1 female (slide, CNC). Mississippi: Tishomingo Co.: McDougal Branch beside Natchez Trace Parkway 2 km southwest of Rt. 25, 18 September 1991, IMS — 1 male (slide, CNC). Missouri: Barry Co.: Roaring River, Eagle Rock, 6 July 1961, DRC — 1 paratype female (slide, CNC). Crawford Co.: Huzzah Creek, Red Bluff Campground off Road V east of Davisville, 26 June 1987, IMS — 3 males, 2 females (slides, CNC), 1 male, 2 females (GAW, CNC). Dent Co.: Meramec River beside Rt. 19, 11 miles (17.6 km) northeast of Salem, 19 July 1960, DRC — 2 paratype females (slides, CNC); 1 July 1961, DRC — 1 deutonymph (slide, CNC). West Fork of Huzzah Creek beside Rt. 32 at Dent Co. Road 524, 4.5 km east of Howes Mill, 10 September 1994, IMS — 1 female (slide, CNC). McDonald Co.: Buffalo Creek beside Rt. 43 just south of Rt. 76, Tiff City, 2 May 1996, IMS — 1 female (slide, CNC). Reynolds Co.: Black River beside Road CC 5 miles (8 km) west of Gads Hill, 8 July 1960, DRC — 1 paratype male (slide, CNC). Shannon Co.: Jacks Fork River, Alley Spring State Park, 13–14 July 1960, DRC — holotype male, allotype female (slides, FMNH), 3 paratype males, 6 paratype females (slides, CNC), 3 paratype males (GAW, CNC). Wayne Co.: St Francis River, Sam A. Baker State Park, 9 July 1960, DRC — 1 paratype male (slide, CNC); 24–26 June 1961, DRC — 2 paratype males, 1 paratype female (slides, CNC), 1 paratype male, 6 paratype females (GAW, CNC). Big Lake Creek beside Road FF northwest of Rt. 67, 27 June 1987, IMS — 3 males, 3 females (slides, CNC), 1 male, 9 females (GAW, CNC). New York: Hamilton Co.: East Branch of Sacandaga River beside Rt. 8, 3.5 km northeast of Rt. 30 near Griffin, 7–8 July 1989, IMS — 2 males, 3 females (slides, CNC), 1 male, 3 females (GAW, CNC). Ohio: Hocking Co.: Stream, Cedar Falls State Park, 18 July 1967, DRC — 1 male (slide, CNC). Oklahoma: Comanche Co.: Stream beside road just south of Wichita Mountains National Wildlife Reserve, 4.5 miles (7.2 km) north of Indiahoma, 14 July 1961, DRC — 3 paratype females, 1 paratype deutonymph (slides, CNC); 12 May 1977, DRC — 2 females (slides, CNC); 2 July 1987, IMS — 5 females (slides, CNC), 7 females (GAW, CNC). Stream beside road at boundary of Wichita Mountains National Wildlife Refuge north of Cache, 3 July 1987, IMS — 1 female (slide, CNC). Delaware Co.: Stream beside Rt. 116, 1 mile (1.6 km) west of Colcord, 7 July 1961, DRC — 1 paratype male, 1 paratype female (slides, CNC). Pushmataha Co.: Stream beside Rt. 271, 1 mile (1.6 km) north of Albion, 9 July 1961, DRC — 2 paratype females (slides, CNC); 15 October 1970, DRC — 1 female (slide, CNC). Walnut Creek beside Rt. 271 south of Albion, 9 July 1961, DRC — 1 paratype male, 3 paratype females (slides, CNC); 1 July 1987, IMS — 2 males, 1 female (slides, CNC). Tennessee: Monroe Co.: Turkey Creek beside Forest Road 35, 2.9 km northeast of road from Rt. 165 to Miller Chapel Church, 20 September 1991, IMS — 2 males, 10 females (slides, CNC), 1 female (GAW, CNC). Wayne Co.: Glenrock Branch Creek at Lower Glenrock Branch Picnic Area beside Natchez Trace Parkway, 2 June 1992, IMS — 5 males, 10 females (slides, CNC). Jacks Branch at Jacks Branch Picnic Area beside Natchez Trace Parkway, 2 June 1992, IMS — 1 male (slide, CNC). Virginia: Bath Co.: Little Back Creek beside Rt. 39, 3 miles (4.8 km) from West Virginia border, 25 July 1964, DRC — 1 male (slide, CNC). Cowardin Run (tributary of Jackson River) beside Road 287, 1.5 miles (2.4 km) southwest of Bacova, 9 September 1968, DRC — 1 female (slide, CNC); 15 July 1990, IMS — 2 females (slides, CNC). Montgomery Co.: Craig Creek, Caldwell Fields Campground near Blacksburg, 12 July 1990, IMS — 1 male, 2 females (slides, CNC). Page Co.: Cub Run beside Forest Road 65, 2 km south of Forest Road 375 near Catherine Furnace, 26 September 1991, IMS — 1 male, 1 female (slides, CNC).

Distribution. Streams in mountainous areas of central and eastern North America from the Ozark Plateau through the Appalachian Mountains and the Maritime Provinces of Canada.

Remarks. Adults of Diamphidaxona pallida resemble those of the preceding five species in that the projections covering the insertions of the fourth pair of legs are long and extend anteriorly parallel to the edges of the ventral shield, and also resemble D. parvacetabula in that the suture lines between the third and fourth coxal plates have the medial loops deeply arched. They differ from adults of D. parvacetabula in that the genital field of males is wider with the acetabula larger in size and the anterior pair closer to the posterior two pairs.

Figures

FIGURES 54 – 61. Diamphidaxona (s. s.) pallida Cook. 54 – 60, adults: 54, dorsal shield, female; 55, leg I, female; 56, ventral shield and genital field, male; 57, pedipalp, male; 58, gnathosoma, lateral view, male; 59, ventral shield and genital field, female; 60, distal segments of leg IV, female; 61, deutonymph, venter of idiosoma with dorsal plates shown by dotted lines.

FIGURES 95 – 100. Diamphidaxona (s. s.) pallida Cook, scanning electron micrographs of adults. 95, dorsal habitus, male; 96, anterior dorsal plate, male; 97, detail of setae on left side of anterior dorsal plate, male; 98, medial view of pedipalp, male; 99, medial view of tarsus of pedipalp, male; 100, lateral view of tarsus of pedipalp, male.

FIGURES 101 – 106. Diamphidaxona (s. s.) pallida Cook, scanning electron micrographs of adults. 101, ventral habitus, male; 102, ventral habitus, female; 103, glandularium of coxal plate IV and looped suture line between coxal plates III and IV, male; 104, detail of glandularium of coxal plate IV, male; 105, genital field, male; 106, dissimilar pairs of glandularia posterolaterally on posterior dorsal plate, male.