Hydrachna fissigera Koenike, 1898

Gerecke, Reinhard, 2020, The early derivative water mites (Acari: Hydrachnidia, superfamilies Eylaoidea, Hydrachnoidea and Hydryphantoidea) of Madagascar, Zootaxa 4727 (1), pp. 1-77 : 13

Hydrachna fissigera Koenike, 1898

Fig. 7 c – e

New record: MD 241, Antsohihy, eau stagnante, octobre 1949. Paulian leg., 1 male; slide mounted, Ac 1234, MNHN Paris.

Remark: The specimen from Antsohihy represents the second record of the species after its first description. It shows the name-giving deep anterior indentation of the genital plate, but does not agree in other characters given in the first description: Neither the papillae are more strongly developed in the posterior part of idiosoma, nor the posterior margin of Cx-I+II is formed by the Cx-II only–both, Cx-I and –II add equal parts at the formation of this part of the plate ( Fig. 7 c ). Interestingly, a large part of the circular structures appearing to represent acetabula, at higher magnification reveal to be setal pores, scattered all over the genital field except for the anterior and lateral border area ( Fig. 7 d ).

Figures

FIGURE 7. Family Hydrachnidae, genus Hydrachna (a.–b., k.–l. from Koenike 1898, f., m. from Gerecke 2004, g.–i. from Lundblad 1946). a.–b. H. signata genital fields; a. male; b. female; c.–e. H. fissigera male; c. coxae and genital field; d. genital plate at higher magnification; e. palp; f. H. amplexa male frontal shield; g.–i. H. madagascariensis male; g. frontal area; h. gnathosoma with palp; i. Cx-IV; k.-l. H. propinqua deutonymph; k. Cx-III+IV and right genital sclerite; l. palp; m. H. mirifica male chelicera.