GENEKIC CLASSIFICATION OF APHIDIDAE. 49 
Genus MICROSIPHUM Cholodkovsky. 
1908. Microsiphum Cholodkovsky, Zool. Anz., v. 32, p. 687. 
Characters. — Head without prominent antennal tubercles, although with apparent 
ones. Antennae of six segments, rather long and slender. Fore wings with the media 
twice branched; hind wings with both media and cubitus present. Cornicles very 
short, not much longer than wide and often scarcely visible in the alate form. Cauda 
extremely short and subcorneal or slightly rounded; anal plate rounded. 
Type (monotypical), Microsiphum ptarmicae Choi. 
Genus PERGANDEIDIA Schouteden. 
Plate VI, KE-MM. 
1903. Pergandeidia Schouteden, Zool. Anz., v. 26, p. 685. 
1913. Longicaudus Van der Goot, Tijd. voor Ent., v. 56, p. 146. 
1915. RMzoberlesia Del Guercio, Redia, v. 10, p. 246. 
1918. Yezosiphum Matsumura, Trans. Sapporo Nat. Hist. Soc, v. 7, pt. 1, p. 7. 
1918. Brachyunguis Das, Mem. Ind. Mus., v. 6, p. 227. 
The genus Pergandeidia was erected by Schouteden with his 
ononidis as type. The characterization of the genus in this paper is 
based on specimens of the species received from Schouteden, and 
though it does not agree with the characterization of the genus as 
sometimes given, it seems necessary to follow the type species in 
forming a conception of the genus. In 1913 Van der Goot erected 
the genus Longicaudus and placed trirliodus Walker as type. In 
studying this species differences sufficient for good generic distinc- 
tion have not been found, and, therefore, the conclusion may be 
drawn that Longicaudus is a synonym of Pergandeidia. Del Guercio 's 
genus is placed here also, although a study of the type species, which 
is not available, possibly may show the cauda to be somewhat different. 
Characters. — Head with no prominent antennal tubercles; antennae of.six segments. 
Fore wings with media twice branched, hind wings with both media and cubitus 
present. Cornicles very short, almost as wide as long. Cauda very long and broad. 
Type (monotypical), Pergandeidia ononidis Schout. 
Genus RHOPALOSIPHUM Koch. 
Plate VI, FF-JJ. 
1854. Rhopalosiphum Koch, Die Pflanz. Aphiden, p. 23. 
1860. Siphocoryne Passerini, Gli Afldi, p. 28. 
1882. Rhopalosiphon Scudder, Nomenclator Zoologicus. 
1910. Coloradoa Wilson, Ann. Ent. Soc. Am., v. 3, p. 323. 
1915. Siphonaphis Van der Goot, Beitrage zur Kennt. d. Holl. Blattlause, p. 238. 
1918. Stephensonia Das, Mem. Ind. Mus., v. 6, p. 175. 
1856. (Type fixation) Gerstaecker, Bericht for 1854, p. 162. 
There has been much confusion in regard to this genus. Koch 
included a number of diverse species. In 1856 Gerstaecker defi- 
nitely set Aphis nympJieae L. as type. Overlooking this, Passerini 
in 1860 set persicae Sulz, as type. In 1863, however, he changed this 
name to diantM Schrank. In 1860 Passerini erected the genus Sipho- 
coryne with A, nympheae L, as type. Having the same type this 
must, therefore, become a synonym of Rhopalosiphum. In 1863 
Passerini placed nymplieae in Rhopalosiphum, although he set dianihi 
141613°— 20— Bull. 826 4 
