Testudacarinae Cook, 1974

O'Neill, Joseph C., Fisher, J. Ray, Nelson, Whitney A., Skvarla, Micheal J., Fisher, Danielle M. & Dowling, Ashley P. G., 2016, Systematics of testudacarine torrent mites (Acari, Hydrachnidia, Torrenticolidae) with descriptions of 13 new species from North America, ZooKeys 582, pp. 13-110 : 21-22

Taxon classification Animalia Trombidiformes Torrenticolidae

Testudacarinae Cook, 1974

Testudacarinae Cook 1974: 145-146; Imamura 1976: 279; Fuste 1980: H7; Viets 1987: 222, 724; Bader 1988: 90; Smith and Cook 1991: 529, 552, 564-565, 574, 582; Cramer 1992: 13-14; Wiles 1997a: 192, 194, 199-200, 205, 209; Harvey 1998: 67; Smith and Cook 1999: 115; Smith et al. 2001: 579, 592, 608, 625, 645; Guo and Jin 2005: 70; Abé 2005: 120; Abé 2006: 6; Davids et al. 2007: 243; Goldschmidt 2007: 444; Boyaci and Özkan 2008: 364; Walter et al. 2009: 264; Zhang and Guo 2010: 117-118; Jin et al. 2010: 111; Smith et al. 2010: 492, 522, 535, 550, 566; Guo and Zhang 2011: 46, 48-49; Esen and Erman 2014: 39; Proctor et al. 2015: 622; Fisher et al. 2015: 83-84.

Subfamilial diagnosis.

For larval diagnosis see Smith (1982). Adults differ from torrenticolines in having three pairs of acetabula (six in Torrenticolinae ); condyles present over the insertions of leg-IV; long posterio-dorsal subcapitular apodemes (also long in Monatractides ); a ridge extending anteriorly from the leg-IV socket; and a ring of platelets closely affiliated with the central dorsal plate, i.e., not hidden within a dorsal furrow as in torrenticolines (Fig. 1). They are further characterized by having a single anterio-medial dorsal platelet and pedipalps without ventral projections, although some torrenticolines also have these characters. Testudacarinae can be further diagnosed by the following combination of characters. Medial dorsal plate exhibiting secondary and occasionally tertiary sclerotization. Dorsal platelets variable in size, shape, and coloration. Anterio-medial platelet smaller than anterio-lateral platelets and trapeziform (rounded to rectangular). Anterio-lateral platelets long with anterior bulge and posterior tapering. Seven pairs of lateral platelets present. Lateral-platelet-2, -4, and -6 large and elongate and -1, -3, -5, and -7 smaller and rounded. Lateral-platelet-3 highly variable and positioned either anterior or lateral to lateral-platelet-4. Lateral-platelet-4 highly variable in shape mostly depending on lateral-platelet-3 position. Dorso-glandularia-2 and post-ocularial setae located together on anterio-lateral platelet. Dorso-glandularia-3, -5, and -6 located on lateral-platelet-1, -5, and -7 respectively. Dorso-glandularia-4 located on the large medial dorsal plate. Latero-glandularia-4 located on lateral-platelet-3. Ventro-glandularia-3 posterior to coxae-IV (on coxae-IV in other torrenticolids). Coxo-glandularia-4 located at tip of coxae-I (as in Monatractides and many Torrenticola ). Pedipalp, femur, and genu with plumose setae ventrally. Also similar to Monatractides , posterio-dorsal subcapitular apodemes are long. Rostrum short.

Distribution.

Testudacarines have been reported on many occasions outside of their original descriptions. Furthermore, the Canadian National Collection in Ottawa, Canada includes thousands of testudacarines collected from across most of North America ( Smith et al. 2010). In Asia there have only been a handful of additional reports ( Walter 1929, Pešić and Smit 2007, Jin et al. 2010, Morimoto 2012). This is not completely due to a lack of torrenticolid work in Asia, for an extensive list see Walter et al. (2009, pg. 256) and Fisher et al. (2015). Extensive work has also been done on water mites in Europe, Africa, and Australia without any reports of testudacarines. Therefore, testudacarines are currently thought to be widely distributed throughout most of North America (with southern limits in Mexico and northern limits around the 60th parallel), and sparsely distributed in parts of Asia.

Remarks.

The three pairs of acetabula, coxae-IV condyles, and “generalized” pedipalps are plesiomorhphic states that clearly show testudacarines as retaining ancestral torrenticolid characteristics ( Wiles 1997a). Wiles (1997a) and other authors suggest latero-glandularia-3 is present on the dorsum of testudacarines. However, we suggest that this is latero-glandularia-4 due to its posterior-most positioning. We also detail sexually dimorphic characters (Fig. 7). Although Habeeb (1954) first noted differences between the sexes of Testudacarus vulgaris , he did not present these distinctions in their wider context as overall conditions of Testudacarinae . Sexual dimorphism present in Testudacarinae include: 1) female dorso-glandularia-4 positioned closer to the muscle scars; 2) dorsal secondary sclerotization always present in females and usually absent in males (very small if present in males); 3) female coxae-II+III midline short; 4) genital field almost entirely enveloped by coxal field in females but only around half of male genital field within coxal field; 5) females idiosoma larger and rounder (males around 80% of female size) with less of the ventral shield composed of coxal field; and 6) excretory pore well separated from ventral line of secondary sclerotization in females, and is either in direct contact with or nearly so in males.