Diamphidaxona

Smith, Ian M. & Cook, David R., 2006, North American species of Diamphidaxona (Acari: Hydrachnida: Hygrobatidae), Zootaxa 1279, pp. 1-44 : 6-7

Diamphidaxona (s. s.) imamurai Cook

( Figs. 8–15 )

Diamphidaxona imamurai Cook, 1974 , pp. 461­462, figs. 1510, 1512, 1514; male.

Description. Character states of Diamphidaxona (s. s.). Dorsal edge of camerostome strongly acutely angled anteriorly and projecting beyond anterior end of idiosoma ( Figs. 10, 15 ). Pedipalps with tibia bearing one ventral seta and tarsus with ventral spine­like seta smooth ( Fig. 11 ). Dorsal shield with anterior plate of same maximum width as posterior plate and broadly rounded anteriorly ( Figs. 8, 13 ). Ventral shield with suture lines between third and fourth coxal plates with medial loops shallow and lateral loops U­shaped and open anteriorly ( Figs. 10, 15 ). Projections covering insertions of fourth pair of legs with anterior extensions moderately long and directed anterolaterally ( Figs. 10, 15 ). Genital field of males fused with ventral shield ( Fig. 10 ). Measurements: Male (n=4): Length/ width anterior dorsal plate 114–124/238–282, length/width posterior dorsal plate 238–267/ 238–282, length/width ventral shield 361–391/257–312, length/width genital field 59–64/ 92–103. Lengths pedipalp segments: Tr 8–11, Fe 31–35, Ge 20–23, Ti 35–39, Ta 20–23. Lengths leg segments: ITr 30–35, IBFe 45–50, ITFe 43–45, IGe 55–58, ITi 50–55, ITa 46–53; IITr 28, IIBFe 43–48, IITFe 40–45, IIGe 48–50, IITi 49–53, IITa 54–60; IIITr 33–38, IIIBFe 38–45, IIITFe 40–43, IIIGe 45–50, IIITi 50–55, IIITa 53–63; IVTr 69–73, IVBFe 58–65, IVTFe 63–70, IVGe 68–73, IVTi 68–75, IVTa 63–70. Female (n=2): Length/width anterior dorsal plate 109–124/238, length/width posterior dorsal plate 243–267/235–243, length/width ventral shield 359–371/262–267, width genital field 89–94. Lengths pedipalp segments: Tr 10, Fe 34–35, Ge 21–24, Ti 38–40, Ta 21–23. Lengths leg segments: ITr 35, IBFe 43–48, ITFe 41–46, IGe 48–58, ITi 45–53, ITa 50–53; IITr 35, IIBFe 40–48, IITFe 40–43, IIGe 45–50, IITi 50, IITa 54; IIITr 28–33, IIIBFe 44–50, IIITFe 43–45, IIIGe 53–55, IIITi 50–58, IIITa 53–65; IVTr 70–80, IVBFe 60–68, IVTFe 55–68, IVGe 60–73, IVTi 60–73, IVTa 58–68.

Specimens examined. Arizona: Cochise Co. : Silver Creek Spring beside Silver Creek Road 4.1 km north of Forest Road 42 between Portal and Paradise, 11 October 1993, IMS — 1 male (slide, CNC). Chiricahua Mountains west of Portal: Cave Creek at John Hand Picnic Area off Forest Road 42A, 12 October 1993, IMS— 1 female (slide, CNC); North Fork of Cave Creek beside Forest Road 42, 1.6 km above Forest Road 42A, 13–23 May 2000, IMS— 1 male (slide, CNC); 6–7 May 2002, IMS— 1 male, 1 female (slides, CNC). Santa Cruz Co.: Sonoita Creek beside Rt. 82 south of Patagonia, 17 July 1987, IMS— 1 male (slide, CNC). New Mexico: Catron Co.: rheocrene spring beside Rt. 180, 5 miles south of Rt. 12, 22 October 1970, DRC — holotype male (slide, FMNH).

Distribution. Streams in southwestern New Mexico and southeastern Arizona.

Remarks. Adults of Diamphidaxona imamurai differ from those of all other known North American species of Diamphidaxona (s. s.) except D. cramerae in that the pedipalps are relatively small and the dorsal edge of the camerostome is strongly acutely angled anteriorly and extends beyond the anterior edge of the idiosoma. They differ from those of D. cramerae in that the dorsal shield is broadly rounded anteriorly and the suture lines between the third and fourth coxal plates have the medial loops relatively shallow and the lateral loops U­shaped and open anteriorly.

Figures

FIGURES 8 – 15. Diamphidaxona (s. s.) imamurai Cook, adults. 8, dorsal shield, male; 9, leg I, male; 10, ventral shield and genital field, male; 11, pedipalp, male; 12, gnathosoma, lateral view, female; 13, dorsal shield, female; 14, distal segments of leg I, male; 15, ventral shield and genital field, female.