Polyarthra

José, Susana B., Paggi, De & Paggi, Juan C., 2011, A new species of Polyarthra Ehrenberg, 1834 belonging to the vulgaris- group (Rotifera: Monogononta: Synchaetidae) from Argentina, with a key to the identification of species in the Neotropical Region, Zootaxa 2828, pp. 51-57 : 56

Key to the identification of Polyarthra species in the Neotropical Region

1 Accessory pair of ventral paddles absent................................................................... 2

- Accessory pair of ventral paddles present................................................................... 3

2 Major paddles lanceolate, broad, 5 to 7 times as long as width, teeth with oblique, submarginal pleats. Inner margin of anterior part of rami, before to the major tooth, denticulate, posterior part smooth. Manubria stout, 11–12 times as long as mean width; with an outer angular projection medially....................................... Polyarthra major Burckhardt, 1900

- Major paddles ensiform, narrow, 10 to 14 times as long as width, teeth without submarginal pleats. Inner margin of anterior part of rami, before the major tooth, smooth, posterior part, denticulate. Manubria slender, 30 to 32 times as long as mean width; without any projection................................................. Polyarthra remata Skorikov, 1896

3 Major paddles homogeneous in shape, fulcrum shorter or longer than rami....................................... 4

- Major paddles heterogeneous in shape, fulcrum as long as rami................................................ 5

4 Major paddles narrow, 12–13 times as long as width; accessory ventral paddles bristle-like; anterior half of inner margin of rami finely denticulate; unci with three teeth; fulcrum longer than rami............... Polyarthra longiremis Carlin, 1943

- Major paddles moderately broad, 5–7 times as long as width; accessory ventral paddles ligulate with denticulate margin; inner margin of rami with anterior third broadly rounded and middle third asymmetrical, with two teeth and one semicircular concavity at one side, and one tooth followed by a semicircular expansion at the other side; unci with single tooth; fulcrum shorter than rami................................................................... Polyarthra vulgaris Carlin, 1943

5 Major paddles similar in shape, but those of ventrolateral bundles widest at distal half and those of dorsolateral paddles widest at proximal half; accessory paddles broad, lanceolate with serrated edges; manubria with lamella; manubria and unci, practically equal in length; no lateral expansion of dorsal integument.................... Polyarthra luminosa Kutikova, 1962

- Major paddles within all bundles with the same pattern of shapes, one ensiform plus two lanceolate; accessory paddles narrow, ligulate with smooth edges; manubria without lamella; unci definitely shorter than manubria; dorsal integument with a pair of lateral, normally angled, expansions................................................ Polyarthra platensis sp. nov.