halacarid

Bartsch, Ilse, 2018, Freshwater halacarid mites (Acari: Halacaridae) from Madagascar - new records, keys and notes on distribution and biology, Bonn zoological Bulletin 67 (2), pp. 79-99 : 80

Annotated key to adult Afrotropical freshwater halacarid genera and Madagascar species

1a. Genu and telofemur of leg I almost equal in length. Tarsus I with ventromedial spur and pair of short ventral setae. .................................... Lobohalacarus Remarks. In the Afrotropical region, the genus Lobohalacarus is represented by a single species, L. weberi . The majority of the individuals have a frontal spine whereas the anterior margin of the other freshwater species is arched or truncate.

1b. Genu of leg I shorter than telofemur I. Tarsus I with 0–1 ventral setae...................................................... 2

2a. Gland pores inconspicuous or absent. ..................... 3

2b. Dorsum with four to five pairs of distinct gland pores (glp), pair of glp-1 on AD, glp-2 marginally in striated integument, glp-4 and glp- 5 in striated integument lateral to PD. ........................................ 4

3a. With four dorsal plates ( AD, pair of OC and PD) and four ventral plates (AE, pair of PE and GP). OC with cornea and large spot of black eye pigment (> 10 µm in diameter). ....................................... Porohalacrus Remarks. The only Porohalacarus species known from Madagascar and Africa, P. alpinus , is characterized by its spots of dark eye pigment, a small one on the AD and a larger one on each OC. The other Madagascan freshwater halacarids have either faintly brown or no eye pigment.

3b. With dorsal shield ( AD and PD fused, OC reduced or fused with PE) and ventral shield (AE, PE and GP fused). Neither cornea nor eye pigment present. ...... .......................................................... Ropohalacarus Remarks. A single species is known from Madagascar, namely Ropohalacarus pallidus . A record of another species, R. uniscutatus , is from northern Africa (Bartsch 2013). Distinguishing characters are outlined below.

4a. Genital acetabula in posterior part of GP, none situated anterior to the level of GO. Length of anal sclerites about half that of female genital sclerites. ............... ............................................................ Soldanellonyx Remarks. At present, Soldanellonyx monardi is the only Soldanellonyx species with records from the Afrotropical region. Worldwide nine species have been described.

4b. Genital acetabula arranged in line along lateral margin of GP (or area representing this plate), most anterior acetabula situated well anterior to GO. Anal sclerites less than 1/3 of the size of genital sclerites. ................................................................................. 5

5a. OC not including platelet with gland pore. Ventral plates AE, PE and GA separated by striated integument. Claws I apically with few, delicate tines, basally with lamellar process with about four tines. ...................................... Limnohalacarus cultellatus

5b. OC including platelet with gland pore. All ventral plates fused. Claws I with J-shaped arranged pectines bearing at least 15 long tines. ................................... ............................................. Limnohalacarus novus Remarks. These two Limnohalacarus species are recorded from Madagascar but further species are mentioned from Africa. All African species are outlined below, after the presentation of L. novus.