Disparalona, Fryer, 1968

Neretina, Anna N., Garibian, Petr G., Sinev, Artem Y. & Kotov, Alexey A., 2018, Diversity of the subgenus Disparalona (Mixopleuroxus) Hudec, 2010 (Crustacea: Cladocera) in the New and Old World, Journal of Natural History 52 (3 - 4), pp. 155-205 : 186-189

3. Disparalona (M.) cf. striatoides ( Šrámek-Hušek 1946) in Africa

( Figures 16 – 18 )

Synonymy

Europe. Pleuroxus striatoides Šrámek-Hušek, 1946, p. 232 , figures 1(b, d, e), 2(a – b) Pleuroxus chappuisi in Šrámek-Hušek et al., 1962, pp. 374 – 375, figure 140(g – l)

Alonella hamulata in Floessner, 2000, pp. 283 – 285, figure 106(a – h) (not i – j!) Disparalona hamata in Kotov et al., 2010, p. 263, pl. 150: figure 1 – 2

Mixopleuroxus striatiodes Šrámek-Hušek in Hudec, 2010, pp. 411 – 414, pl. 101

(?) Disparalona hamata in Illyová and Hudec, 2004, pp. 287 – 288, figure 1

Material examined from Africa.

Ethiopia. Three parthenogenetic females from Dura River (place near the bridge) (N 10.9881°, E 36.4973°), coll . 20 February 2009 by A.A. Kotov, AAK 2009 – 118; 2 parthenogenetic females from Dura River (place near the bridge) (N 10.9881°, E 36.4973°), coll . 20 February 2009 by A.A. Kotov, AAK M-1442; 1 parthenogenetic female from Qashiny Dam ( River diversion), coll . March 2016 by W. Zelalem, ANN 2016 – 011. Republic of South Africa. Three parthenogenetic females from Plattenkloof River, fall rockpools, Wildcliff Nature Reserve , Western Cape, coll . 18 July 2008 by Z. Gido, HNHM; 2 females from a swampy meadow pool near Wildekranz River, Wildcliff Nature Reserve , Heidelberg District, coll . 19 July 2008 by Z. Gido, HNHM; (?) 1 parthenogenetic female (exuvium only) from Botanical Gardens Dam, Grahamstown (S 33.3166°, E 26.515°), Eastern Cape, coll . 24 November 1989 by K. Martens, de Moor and Barber, NNS 2002 – 174.

Short diagnosis

Fine details of morphology completely correspond with D. hamata and D. chappuisi redescribed above. Found differences concern: (1) body shape (presence of prominent dorsal keel); (2) shape of rostrum (dorsal edge of rostrum and head form broadly

rounded portion, while in D. hamata and D. chappuisi they form more or less narrowly rounded portion).

Distribution

We are not fully sure of the identity of African and South European populations. To date, striatoides -like forms are detected through all Africa (from the Republic of South Africa to Ethiopia) and Europe ( Czechia and Slovak Republic). Šrámek-Hušek et al. (1962) synonymized P. striatoides with D. chappuisi and concluded that European populations appear as a result of anthropogenic introduction. But we found that such synonymization was wrong, i.e. the opinion of a human-mediated introduction must be specially checked: European populations in reality could belong to an endemic indigenous taxon.

Taxonomic comments

We found a significant difference between African populations in the rate of the dorsal keel development and concluded that there are two species in Africa, D. (M.) chappuisi and D. (M.) cf. striatoides . But we note that identification based only on shape of body (due to differences in the keel development) may be controversial, confusing and useless for discrimination of sibling species, as already shown for some other chydorids (e.g. Sinev 2009; Sinev and Elmoor-Loureiro 2010; Sinev et al. 2012). Further investigations of African, South European and Australian populations described as D. caudata ( Smirnov, 1996a, 1996b), including description of gamogenetic females and males and genetic comparison, are desirable in order to clarify the status of all striatoides -like forms.

In Ethiopian samples AAK 2009 – 118 and AAK M-1442 we found both species (identified here as D. chappuisi and D. cf. striatoides ) without any transitional forms; this may be a sign of their reproductive isolation. Note that where only deformed specimens or exuvia ( Figure 19 ) are found in samples, identification of these two Old World taxa, at least in Africa, is very difficult, or even impossible.

Figures

Figure 16. Disparalona (M.) cf. striatoides (Šrámek-HuŠek, 1946), parthenogenetic female from Dura River, Ethiopia. (a) Adult parthenogenetic female, lateral view; (b) adult parthenogenetic female, dorsal view; (c) head; (d) head pores and ornamentation of head shield; (e) labrum; (f) valve; (g) armature of posteroventral portion of valve, inner view; (h) armature of ventral portion of valve, inner view; (i) armature of anterior portion of valve, inner view; (j) ornamentation of posteroventral portion of valve, outer view; (k) ornamentation of central portion of valve, outer view; (l) ornamentation of anterior portion of valve, outer view. Scale bars 0.1 mm.

Figure 17. Disparalona (M.) cf. striatoides (Šrámek-HuŠek, 1946), parthenogenetic female from Dura River, Ethiopia. (a) Postabdomen; (b) distal portion of postabdomen and postabdominal claw, outer view; (c) antenna I; (d) antenna II, general view; (e) exopod and endopod of antenna II; (f) limb I. Scale bars 0.1 mm.

Figure 18. Disparalona (M.) cf. striatoides (Šrámek-HuŠek, 1946), parthenogenetic female from Dura River, Ethiopia. (a) Limb II; (b) limb III; (c) limb IV; (d) exopodite of limb IV; (e, f) fragments of gnathobase and filter plate of limb IV; (g) limb V. Scale bars 0.1 mm.

Figure 19. Disparalona (Mixopleuroxus) sp.?, parts of exuvium of a parthenogenetic female from Botanical Gardens Dam, Grahamstown, Eastern Cape, the Republic of South Africa. (a) Labrum; (b) exopod and endopod branches of antenna II; (c) limb I; (d) IDL of limb I; (e) limb II. Scale bars 0.1 mm.