Unionicola (Dimockatax) tumida (Wolcott 1898) Plates in Vidrine (1996a)

Transcription

1 Synonomy-- Unionicola (Dimockatax) tumida (Wolcott 1898) Plates in Vidrine (1996a) Atax tumidus Wolcott 1898 in Wolcott 1898 and 1899, Piersig 1901 Unionicola (Parasitatax) tumida (Wolcott 1898) in Mitchell 1954, Viets and Plate 1954, Viets 1956 and 1957, Crowell 1961, Habeeb 1967, Vidrine 1977b, 1980a, and 1986e, and Vidrine and Bereza 1978b. Unionicola (Dimockatax) tumida (Wolcott 1898) in Vidrine 1992b, Vidrine 1996a-e, Edwards and Vidrine Etymology-- Named for its tumescent (swollen) body. Museum type number(s) and location-- Marshall Collection, Field Museum of Natural History, Chicago, Illinois. Type locality and host-- From Anodontoides ferussacianus (Lea) from Michigan. Diagnosis-- Character states of the subgenus; dorsum apparently lacking a dorsal plate; coxal plates abbreviate and with distinct borders; female acetabular plates with an elongate, bird-bill-like spinous process; male acetabular plates with more than 20 acetabula each; pedipalps thick; pedipalp Ta smoothly curved ventrally with 2, very small clawlets that are somewhat indistinct; all tarsal claws of walking legs bifid with the dorsal prong shorter than the ventral prong; first walking leg with short setae; fourth walking leg Ta nearly straight; body light in color. Male (7 specimens)-- Length including capitulum 1150 ( ); length of posterior coxal group 298 ( ); dorsal lengths of pedipalp segments: Ti 102 (80-110); Ta 75 (68-80); dorsal lengths of leg segments: leg I: TFe 137 ( ); Ge 167 ( ); Ti 173 ( ); Ta 125 ( ); leg IV: TFe 221 ( ); Ge 303 ( ); Ti 393 ( ); Ta 286 ( ). Female (7 specimens)-- Length including capitulum 1800 ( ); length of posterior coxal group 342 ( ); dorsal lengths of pedipalp segments: Ti 116 ( ); Ta 79 (75-80); dorsal

2 lengths of leg segments: leg I: TFe 167 ( ); Ge 217 ( ); Ti 224 ( ); Ta 143 ( ); leg IV: TFe 324 ( ); Ge 466 ( ); Ti 544 ( ); Ta 349 ( ). Notes-- Unionicola tumida is generally a parasite of members of the mussel subfamily Anodontinae. It is not commonly found in the genera Anodonta and Pyganodon in North America. A single population of Utterbackia imbecillis from upper Bayou Cocodrie in Louisiana is unusually parasitized by this mite. More detailed study may recognize this latter population as distinctive. There is a high probability that local populations currently assigned to this species are indeed distinctive. Discussion-- With the white, swollen bodies, this divergent subgenus grossly resembles Najadicola ingens (Koenike 1895) (Pionidae: Najadicolinae), which is another mite that inhabits mussels in the Northern Hemisphere (Simmons and Smith, 1984). The 5 species in Dimockatax are essentially unstudied; however, they comprise a uniquely divergent group. This is the first species described and discussed (Wolcott 1898 and 1899). I was really surprised to find a close relative in Asian mussels, U. tumidoides Vidrine Also in 1986, I sorted the North American material into 3 species based upon their pedipalps. In 2008, another species, U. ernstingi Edwards et al., was discovered. Hosts: Alasmidonta viridis (Rafinesque): Margaritana deltoides Lea, Michigan? (Wolcott, 1899); Pressodonta calceola Lea in Viets and Plate 1954; Alasmidonta calceola (Lea) (Vidrine, 1980a). Amblema plicata Say (?): Anodonta ovata Lea, Michigan (Wolcott, 1899, and in Viets and Plate 1954) (mussel identification uncertain) (Vidrine, 1980a). Anodontoides ferussacianus (Lea): Anodonta subcylindracea Lea, Michigan (Wolcott, 1899) (and in Viets and Plate 1954). Anodontoides radiatus (Conrad): Strophitus subvexus (= S. radiatus), Louisiana (Vidrine, 1980a). Lasmigona costata (Rafinesque): Missouri (Utterback 1916); Vidrine 1980a. Pyganodon cataracta (Say): New York (Baker 1982).

3 Pyganodon fragilis (Lamarck): Anodonta fragilis, Michigan (Wolcott, 1899), Anodonta marginata Say in Viets and Plate 1954; Anodonta cataracta (Say) Vidrine, 1980a. Strophitus undulatus (Say): Anodonta edentula Say, Michigan (Wolcott, 1899 and in Viets and Plate 1954; Arkansas?, Pennsylvania, and Ohio (Vidrine 1980a); Strophitus subvexus (Conrad), San Jacinto River, Texas (Vidrine 1980a). Utterbackia imbecillis (Say): Anodonta imbecillus Say, Louisiana (Vidrine 1977b and 1980a). Map 70. Distribution of U. tumida (after Vidrine 1996).

4 Figure and plates from Vidrine (1996):

5 Plate 198: Top left: male venter (San Jacinto River, TX). Top right: male venter (Dunning Creek, PA). Bottom left: composite photo of female venter (San Jacinto River, TX). Bottom right: composite photo of female venter (Dunning Creek, PA).

6 Plate 199: Top left: male anterior venter. Top right: female anterior venter. Middle left: male venter. Middle upper right: female venter. Middle lower right: female genital field. Bottom left: male venter. Bottom right: female genital field.

7 Plate 200: Top left: male venter. Top right: female genital field. Middle left: male pedipalps. Middle upper right: leg I. Middle lower right: female pedipalps. Bottom left: tarsus of pedipalp. Bottom right: tarsus of pedipalp.

8 New plates: Plate 1: male venter:

9 Plate 2: male venter:

10 Plate 3: female venter:

11 Plate 4: female venter (newly emerged and not yet swollen):

12 Plate 5: female genital field (note inner flaps appear as bird bill): Plate 6: pedipalps:

13 Plate 7: tarsal claw of pedipalp: Plate 8: male genital field: