CYCLOPINAE Rafinesque, 1815 ACANTHOCYCLOPS Kiefer, 1927 The genus Acanthocyclops Kiefer, 1927 is characterized by leg 5 consisting of two distinct segments, with the distal segment bearing an apical seta and a subapical spine. The subapical spine is relatively short, about the length of the terminal segment. The genus is among the five most speciose of the cyclopoid copepod subfamily Cyclopinae, with more than 75 valid species and subspecies, most cosmopolitanan or holarctic, living in surface or subsurface fresh waters; only few species are strictly subterranean (DUSSART & DEFAYE, 1985; BOXSHALL & HALSEY, 2004) It is widely recognized that some species groups show a high intraspecific morphological (DODSON, 1994; DODSON et al., 2003) and genetic (GRISHANIN et al., 2005) variability. This, together with incomplete descriptions, resulted in many species with an uncertain status (see REID et al., 1991; EINSLE, 1996) and a progressively complex taxonomy that relies on only a few relatively stable characters. This tendency is shared by other genera in the subfamily Cyclopinae (ROCHA, 1998). One of the most relevant cases of taxonomical confusion includes A. vernalis and A. robustus, each of them probably representing a complex of cryptic species (DODSON et al., 2003). Some of these are being described from different geographical areas (MIRABDULLAYEV and DEFAYE, 2002, 2004). Species of Acanthocyclops occur as littoral epibenthic forms in ponds, lakes and groudwater (REID et al., 1991; FIERS et al., 2000) (from: Mercado, Suarez-Morales & Silva-Briano, 2006). The total number of species and subspecies in the genus is to be considered approximate due the great affinity with the genus Diacyclops, as well as the continual transposition of species from Acanthocyclops to Diacyclops and from Diacyclops to Acanthocyclops (Galassi & De Laurentiis, 2004) Some authors (Stoch, 1995; Iepure, 2001) divided the genus into the following species-groups: capillatus, gordani, robustus-vernalis and kieferi (left: A. agamus). Pandourski (1992, 1997) transferred to the genus Acanthocyclops the following Diacyclops species: D. stygius Chappuis, 1924, D. deminutus (Chappuis, 1925), D. macedonicus Petkovski, 1954 and D. chappuisi Naidenow & Pandourski, 1992. Recently Mirabdullayev & Defaye (2002) reviewed the taxonomy of the Acanthocyclops robustus species complex, pointing out that A. robustus s. str. "differs from all the species of the A. vernalis-robustus species complex by the ornamentation of the basipodite of antenna which has spinules near the exopodal seta. A. robustus differs from A. vernalis (sensu European form) in the shape of the genital segment and the apical spines of Enp3P4, which are always shorter in A. vernalis". At present the systematic "status" of the genus is problematic, due to its close affinities with the genus Diacyclops, and a revison of the "Acanthocyclops-Diacyclops" complex is strongly suggested. Acanthocyclops agamus Kiefer 1938 [Italy; ground waters] ** Acanthocyclops americanus (Marsh, 1892) Acanthocyclops americanus f.spinosa Monchenko, 1961 [Ukraine] Acanthocyclops balcanicus balcanicus (Naidenow & Pandourski 1992) [Bulgaria; ground waters] Acanthocyclops balcanicus bisaetosus Iepure, 2001 [Romania; cave waters] Acanthocyclops biarticulatus Monchenko, 1972 (syn. Monchenkocyclops biarticulataus (Monchenko, 1972) Acanthocyclops brevispinosus (Herrick, 1884) [USA; fresh waters] ** Acanthocyclops caesariatus Mercado-Salas et al., 2009 [Mexico; ephemeral waters] Acanthocyclops capillatus (G.O.Sars, 1863) [Euope, north America; fresh waters] Acanthocyclops carolinianus (Yeatmann, 1944) [north America; fresh waters] Acanthocyclops cephallenus Pesce 1978 [Greece, Iran (?); ground waters] Acanthocyclops chappuisi Naidenow & Pandourski 1992 [Bulgaria; ground waters] Acanthocyclops columbiensis Reid, 1990 [Columbia; acid freshwater wetlands] Acanthocyclops deminutus (Chappuis, 1925) [Europe; fresh waters] Acanthocyclops dodsoni Mercado, Suarez-Morales & Silva-Briano, 2006 [Mexico; fresh waters] Acanthocyclops dussarti Pesce & Maggi, 1977 [Greece; wells] (=Acanthocyclops (Megacyclops) Pesce & Maggi, 1977) Acanthocyclops dussarti orientalis Pesce & Maggi, 1982 [Iran; wells] Acanthocyclops eduardoi Mercado-Salas & Álvarez-Silva, 2013 [Mexico; ecological reserve] Acanthocyclops einslei Mirabdullayev & Defaye, 2004 [Europe; fresh waters] (= A. robustus according to Miracle et al. 2013. Acanthocyclops exilis (Coker, 1934) [USA; fresh waters] Acanthocyclops fiersi Mercado Salas et al., 2023 [Mexico] Acanthocyclosp fonticulus Lee & Chang 2007 [Korea; springs] Acanthocyclops gmeineri Pospisil 1989 [Bulgaria; ground waters] Acanthocyclops gordani Petkovski 1971 [Yugoslavie, Italy; fresh surface and ground waters] Acanthocyclops hispanicus Kiefer 1937 [Spain, Italy; ground waters) * Acanthocyclops intermedius Mazepova, 1950 [Baikal Lake] (syn. Diacyclops intermedius (Mazepova, 1952) Acanthocyclops insectus (Forbes S.A., 1882) Acanthocyclops iskrecensis Pandourski 1992 [Bulgaria; ground waters] Acanthocyclops kagaensis Ito 1964 [Japan; ground waters] Acanthocyclops kieferi (Chappuis 1925) [Europe; ground waters] Acanthocyclops kieferi hispanicus Kiefer, 1937 (= Acanthocyclops hispanicus Kiefer, 1937) Acanthocyclops kozminskii (Lindberg, 1942) [Iran; fresh waters] Acanthocyclops longifurcus Shen & Sung, 1963 [Tibet; fresh waters] (syn. Diacyclops longifurcus (Shen & Sung, 1963) Acanthocyclops macedonicus Petkovski, 1954 [Makedonia; ground waters] (syn. Diacyclops stygius macedonicus Petkovski, 1954) Acanthocyclops magistridussarti Stoch & Cristina Bruno, 2011 [Italy; cave, spring, hyphoreic waters] Acanthocyclops marceloi Mercado-Salas et al., 2009 [Mexico; ephemeral waters] Acanthocyclops michaelseni (Mrazek, 1901) [south America; fresh waters] **** Acanthocyclops milotai Iepure Sanda & Defaye, 2008 [South-Eastern Europe; pools] Acanthocyclops mirnyi Borutzky & Vinogradov, 1957 [Antarctic Sea] (syn. Diacyclops mirnyi (Borutzky & Vinogradov, 1957) Acanthocyclops miurai Ito 1957 [Japan; ground waters] Acanthocyclops montana Reid et al. 1991 [USA: wells] Acanthocyclops morimotoi Ito 1952 [Japan; ground waters] Acanthocyclops muscicola (Lastoschkin, 1924) [URSS; mosses] Acanthocyclops niceae (Mann, 1940) [Turkey; fresh waters] (syn. Megacyclops viridis viridis (Jurine, 1820) Acanthocyclops notabilis Mazepova, 1950 [Baikal Lake] Acanthocyclops orientalis Borutzki, 1966 [Italy, Yugoslavie, URSS; fresh surface and ground waters] Acanthocyclops parcus (Herrick, 1882) Acanthocyclops parasensitivus Reid, 1997/98 [U.S.A.; springs] Acanthocyclops parvulus Strayer 1988 [USA; hyporheic] Acanthocyclops pennaki Reid 1992 [USA, hyporheic] Acanthocyclops petkovskii Pesce & Lattinger 1983 [Yugoslavie; ground waters] Acanthocyclops phreaticus (Chappuis, 1928) Acanthocyclops pilosus Kiefer, 1934 Acanthocyclops plattensis Pennak & Ward, 1985 [USA; hyporheic and wells] (syn. Acanthocyclops vernalis vernalis (Fischer, 1853) Acanthocyclops plesai Iepure, 2001 [Romania; cave waters] Acanthocyclops profundus profundus Mazepova, 1950 [Baikal Lake] Acanthocyclops profundus tomilovi Mazepova, 1978 [Baikal Lake] Acanthocyclops propinquus Plesa 1957 [Romania, Bulgaria; ground waters] Acanthocyclops radevi Pandourski 1993 [Bulgaria; hyporheic] Acanthocyclops rebecae Fiers & Ghenne, 2000 [Mexico, Yucatan; temporary pools] Acanthocyclops reductus reductus (Chappuis 1925) [Romania; ground waters] Acanthocyclops rhenanus Kiefer 1936 [Germany; ground waters] Acanthocyclops robustus (G.O. Sars, 1863) [cosmopolitan; fresh surface and ground waters] [PDF2]] Acanthocyclops robustus f. limnetica Petkovski, 1975 [Yugoslavia; lakes] **** Acanthocyclops robustus armata Mastrantuono & Stella, 1976 Acanthocyclops robustus insueta Mastrantuono & Stella, 1976 Acanthocyclops robustus limnetica Petkovski, 1975 Acanthocyclops robustus saxonica Mastrantuono & Stella, 1976 Acanthocyclops robustus setiger Mastrantuono & Stella, 1976 Acanthocyclops robustus typica Mastrantuono & Stella, 1976 Acanthocyclops robustus brevispinosus (Herrick, 1895) (nomen dubium) Acanthocyclops sambugarae Kiefer 1981 [Italy; hyporheic waters] Acanthocyclops sensitivus (Graeter & Chappuis 1914) [Europe; ground waters] [PDF2] Acanthocyclops serrani Braicovich & Timi, 2009 Acanthocyclops signifer Mazepova, 1961 [Baikal Lake ] [syn. Acanthocyclops rupestris signifer Mazepova, 1952] Acanthocyclops similis Flossner, 1984 [Baikal Lake] Acanthocyclops smithae Reid & Suarez-Morales, 1999 [Mexico, Yucatan; streams, ponds] Acanthocyclops skottsbergi Lindberg, 1949 [Patagonia; fresh waters] (syn- Diacyclops michaelseni (Mrázek, 1901) Acanthocyclops strimonis (Pandourski, 1994) [Bulgaria; fresh, ground waters] Acanthocyclops stygius Chappuis, 1924 [Yugoslavi, Romania; ground waters] Acanthocyclops stygius deminutus (Chappuis 1925) [Romania; ground waters] Acanthocyclops stygius macedonicus Petkovski 1954 [Yugoslavia; ground waters] (syn. Acanthocyclops stygius (Chappuis, 1924); Diacyclops stygius stygius (Chappuis, 1924) Acanthocyclops tenuispinalis Shen & Sung, 1963 [Tibet; fresh waters] (syn. Diacyclops tenuispinalis Shen & Sung, 1963) Acanthocyclops tokchokensis Kim & Chang, 1991 [Korea; fresh waters] Acanthocyclops trajani Mirabdullayev & Defaye, 2002 [Europe, Iran, Uzbekistan, Kazakhstan, Tunisia, Canada, U.S.A.; fresh waters] ***** Acanthocyclops transylvanicus Iepure & Oarga, 2011 [Romania; caves] Acanthocyclops troglophilus (Kiefer 1932) [Italy, URSS; ground waters] Acanthocyclops venustoides venustoides (Coker, 1934) [north America; fresh waters] Acanthocyclops venustoides bispinosus (Yeatman, 1951) [north America; fresh waters] *** Acanthocyclops venustus venustus (Norman & Scott 1906) [Europe; URSS; fresh waters] Acanthocyclops venustus stammeri (Kiefer 1930) [Yugoslavie, URSS; ground waters] Acanthocyclops venustus crinitus (Graeter 1908) [Europe; fresh waters] (=Acanthocyclops crinitus (Graeter, 1908))** Acanthocyclops venustus italicus Pesce & Maggi 1979 [Italy; wells] Acanthocyclops venustus troglophilus Kiefer, 1932 Acanthocyclops venustus westfalicus (Kiefer 1931) [Europe; fresh surface and ground waters] Acanthocyclops vernalis (Fischer, 1853) [cosmopolitan; fresh surface and ground waters] Acanthocyclops vernalis aculeata Mastrantuono & Stella, 1976 Acanthocyclops vernalis ambigua Mastrantuono & Stella, 1976 Acanthocyclops vernalis brevispinosus (Herrick, 1895) Acanthocyclops vernalis elongatus (Claus, 1893) Acanthocyclops vernalis infesta Mastrantuono & Stella, 1976 Acanthocyclops vernalis orientalis Borutzky, 1966 Acanthocyclops vernalis ornatus (Jungmayer, 1914) Acanthocyclops vernalis robustus (Sars G.O., 1863) Acanthocyclops vernalis tetracantha Mastrantuono & Stella, 1976 Acanthocyclops vernalis parcus (Herrick, 1882) (= Acanthocyclops parcus (Herrick, 1882) Acanthocyclops viridis (Jurine, 1820) represented as Acanthocyclops viridis viridis (Jurine, 1820) (=Megacyclops viridis viridis (Jurine, 1820) Among all the above taxa three morphological groups, characterized by a 11, 12, 17 -segmented antennula, can be recognized, the most derived including the following species, with female 11- segmented antennula and 2-segmented legs 1 to 4 ("kieferi-group", according to Pandourski, 1997; Galassi & De Laurentiis, 2004 ): agamus, balcanicus balcanicus, balcanicus bisetosus (=Diacyclops bisetosus (Rehberg, 1880), biarticulatus, exilis, hispanicus, hypogeus, iskrecensis, kieferi, michaelseni, notabilis, parvulus, petkovskii, plesai, profundus profundus profundus, profundus tomilovi, propinquus, radevi, reductus, sambugarae, similis, strimonis, transylvanicus. However, the establishment of the above groups deserves further analyis and confirmation. * synonym of A. kieferi (?) *** could be a variation of Acanthocyclops venustoides (Reid et al., 1991) **** synonym of Acanthocyclops trajani (Mirabdullayev & Defaye, 2002) ***** synonyms: A. robustus f. limnetica Petkovski, 1975 ; A. robustus (G.O. Sars, 1863); Dussart et al.(1966), partim; Kiefer (1976). partim, Purasjoki & Viljamaa (1894); Fiers & Einsle (1966), partim; Caramujo & Boavida (1998), and A. americanus (Marsh, 1893) ; Lowndes (1926); Rylov (1948); Dussart (1967, 1969); Monchenko (1961, 1974); Alekseev & Kosova (1976); Alekseev (1995); Miracle et al. (2013). ****** Marque (1991) synonymized with this species Acanthocyclops skottsbergi Lindberg, 1949; Morton (1985) reallocated this species to the genus Diacyclops Acanthocyclops alticola (Kiefer, 1935) (=Diacyclops alticola (Kiefer, 1935) Acanthocyclops arenosus Mazepova, 1950 (= Diacyclops arenosus (Mazepova, 1950) Acanthocyclops bicuspidatus (Claus, 1857) (=Diacyclops bicuspidatus (Claus, 1857) Acanthocyclops brachypus (Kiefer, 1955) (=Megacyclops brachypus Kiefer, 1955) Acanthocyclops ekmani Lindberg, 1950 (= Diacyclops ekmani (Lindberg, 1950) Acanthocyclops elegans Mazepova, 1962 (=Diacyclops elegans (Mazepova, 1962) Acanthocyclops fontinalis Naidenov, 1969 (= Diacyclops fontinalis Naidenov, 1969) Acanthocyclops formosanus Harada, 1931(= Megacyclops formosanus (Harada, 1931) Acanthocyclops galbinus Mazepova, 1962 (= Diacyclops galbinus (Mazepova, 1962) Acanthocyclops hypogeus (Kiefer, 1930) (= Diacyclops hypogeus Kiefer, 1930) Acanthocyclops improcerus Mazepova, 1950 (=Diacyclops improcerus (Mazepova, 1950) Acanthocyclops jasnitskii Mazepova, 1950 (=Diacyclops jasnitskii (Mazepova, 1950) Acanthocyclops jeanneli (Chappuis, 1929) (= Diacyclops jeanneli (Chappuis, 1929) Acanthocyclops konstantini Mazepova, 1962 (= Diacyclops konstantini (Mazepova, 1962) Acanthocyclops latipes (Lowndes, 1927) (= Megacyclops latipes (Lowndes, 1927) Acanthocyclops lobulosus (Ekman, 1905) (= Diacyclops michaelseni (Mrázek, 1901) Acanthocyclops magnus (Marsh, 1920) (= Megacyclops magnus (Marsh, 1920) Acanthocyclops nanus (Sars G.O., 1863) (= Diacyclops nanus nanus (Sars G.O., 1863) Acanthocyclops spongicola Mazepova, 1962 (= Diacyclops spongicola (Mazepova, 1962) Acanthocyclops talievi Mazepova, 1970 (= Diacyclops talievi (Mazepova, 1970) Acanthocyclops thomasi (Forbes S.A., 1882) (= Diacyclops thomasi (Forbes S.A., 1882) Acanthocyclops versutus Mazepova, 1962 (= Diacyclops versutus (Mazepova, 1962) | LIST OF SPECIES FROM WORLD OF COPEPODS at "www.marinespecies.org" | Walter, T.C.; Boxshall, G. (2021). World of Copepods database. Acanthocyclops Kiefer, 1927. Accessed at: https://www.marinespecies.org/copepoda/ Molecular-genetic-based contribution to the taxonomy of the Acanthocyclops robustus group. | LATEST REVISION AUGUST 28. 2023 | Copyright © 1999-2023 G. L. Pesce - All Rights Reserved. Text and images on this website may not be redistributed or put as part of any collection (image archives, CDs etc) without prior written permission