Diamphidaxona parvacetabula, Smith, Ian M. & Cook, David R., 2006

Smith, Ian M. & Cook, David R., 2006, North American species of Diamphidaxona (Acari: Hydrachnida: Hygrobatidae), Zootaxa 1279, pp. 1-44 : 14-15

Diamphidaxona (s. s.) parvacetabula sp. nov.

( Figs. 47–53 )

Description. Character states of Diamphidaxona (s. s.). Dorsal edge of camerostome acutely rounded anteriorly and not projecting beyond anterior end of idiosoma ( Figs. 49, 52 ). Pedipalps with tibia bearing one ventral seta and tarsus with ventral spine­like seta bearing two straight or slightly curved denticles ventrally ( Fig. 51 ). Dorsal shield with anterior plate of same width as posterior plate and rounded anteriorly ( Fig. 47 ). Ventral shield with suture lines between third and fourth coxal plates with medial loops deeply arched and lateral loops U­shaped and open anteriorly ( Figs. 49, 52 ). Projections covering insertions of fourth pair of legs with anterior extensions long and directed anteriorly parallel to edges of ventral shield ( Figs. 49, 52 ). Genital field of males fused with ventral shield but with suture line visible; genital acetabula relatively small and anterior pair widely separated from posterior two pairs ( Fig. 49 ). Measurements: Male (n=5): Length/ width anterior dorsal plate 139–153/228–233 (153/233), length/width posterior dorsal plate 277–337/223–248 (337/248), length/width ventral shield 431–475/277–287 (475/ 280), length/width genital field 79–96/99–114 (96/114). Lengths pedipalp segments: Tr 15–16 (15), Fe 58–65 (65), Ge 40–44 (41), Ti 58–65 (65), Ta 28–30 (30). Lengths leg segments: ITr 35–40 (38), IBFe 53–63 (63), ITFe 55–58 (58), IGe 63–68 (68), ITi 63–68 (68), ITa 75–83 (80); IITr 38–43 (40), IIBFe 55–58 (58), IITFe 53–55 (55), IIGe 58–65 (63), IITi 60–65 (63), IITa 73–78 (75); IIITr 34–40 (40), IIIBFe 48–55 (55), IIITFe 48–50 (48), IIIGe 58–63 (60), IIITi 63–66 (63), IIITa 75–80 (80); IVTr 75–80 (80), IVBFe 73–80 (80), IVTFe 83–90 (90), IVGe 98–105 (105), IVTi 100 (105), IVTa 93–103 (103). Female (n=7): Length/width anterior dorsal plate 149–193/223–302, length/width posterior dorsal plate 307–376/233–302, length/width ventral shield 436–549/282–347, width genital field 99–134. Lengths pedipalp segments: Tr 16–20, Fe 63–71, Ge 40–48, Ti 63–73, Ta 29–35. Lengths leg segments: ITr 33–40, IBFe 63–73, ITFe 61–73, IGe 70–79, ITi 70–80, ITa 80–90; IITr 38–43, IIBFe 60–70, IITFe 55–65, IIGe 63–75, IITi 63–75, IITa 75–85; IIITr 35–43, IIIBFe 55–65, IIITFe 53–63, IIIGe 63–75, IIITi 68–83, IIITa 79–90; IVTr 80–93, IVBFe 78–91, IVTFe 88–103, IVGe 105–123, IVTi 103–125, IVTa 103–115.

Types. Holotype: Male from Calamity Creek beside Rt. 118, 32.8 km south of Rt. 90/ 67 in Alpine, Brewster Co., Texas, 4 October 1999, IMS (slide, CNC). Paratypes: Arizona: Cochise Co. : Chiricahua Mountains west of Portal: Cave Creek at John Hand Picnic Area off Forest Road 42A, 15 July 1987, IMS — 1 female (slide, CNC); 5 March 1999, IMS — 1 male (slide, CNC); 15 September 2001, IMS — 2 females (slides, CNC). Cave Creek at and just above Stewart Campground, 16 July 1987, IMS — 1 male, 3 females (slides, CNC); 9–11 October 1993, IMS — 1 female (slide, CNC); 30 April 2001, IMS — 1 male (slide, CNC); 9 May 2002, IMS — 1 female (slide, CNC). Cave Creek below dam at Herb Martyr Campground off Forest Road 42A, 28 April 2001, IMS — 1 female (slide, CNC); 1 May 2001, IMS — 1 female (slide, CNC). North Fork of Cave Creek beside Forest Road 42, 1.6 km above Forest Road 42A, 8–14 September 2001, IMS — 1 male, 1 female (slides, CNC); 6–7 May 2002, IMS — 1 female (slide, CNC). East Turkey Creek beside Forest Road 42B, 2.2 km north of Forest Road 42, 9 May 1998, IMS — 1 male (slide, CNC). Maricopa Co. : Sycamore Creek off Rt. 87 at Circle Bar Ranch, 27 August 1992, SM Clinton — 1 male (slide, CNC). Sycamore Creek off Rt. 87 at Round Valley, 27 August 1992, SM Clinton — 1 female (slide, CNC). Santa Cruz Co.: Sycamore Creek off Ruby Road west of Nogales, 14 October 1993, IMS — 1 female (slide, CNC). New Mexico: Catron Co.: Little Creek beside Little Creek Trail off Rt. 15, 63 km (39 miles) north of Rt. 180 in Silver City, 16 May 1977, DRC — 1 female (slide, CNC); 17 May 1991, IMS — 1 female (slide, CNC); 25 September 1999, IMS — 1 female (slide, CNC). Texas: Brewster Co.: Same data as holotype — 2 males, 6 females (slides, CNC); same locality as holotype, 28 September 1994, IMS — 1 female (slide, CNC).

Etymology. From the Latin parvus meaning “little” and acetabulum meaning “cup­shaped vessel”.

Distribution. Streams in southeastern Arizona, southwestern New Mexico and southwestern Texas.

Remarks. Adults of Diamphidaxona parvacetabula resemble those of the preceding four species and D. pallida 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. pallida in that the suture lines between the third and fourth coxal plates have the medial loops deeply arched. They differ from adults of D. pallida in that the genital field of males is narrower with the acetabula smaller in size and the anterior pair widely separated from the posterior two pairs.

Figures

FIGURES 47 – 53. Diamphidaxona (s. s.) parvacetabula sp. nov., adults. 47, dorsal shield, female; 48, distal segments of leg IV, female; 49, ventral shield and genital field, male; 50, leg I, male; 51, pedipalp, male; 52, ventral shield and genital field, female; 53, gnathosoma, lateral view, female.