Are Phenacoccus solani Ferris and P. defectus Ferris (Hemiptera: Pseudococcidae) distinct species? Author Chatzidimitriou, Evangelia Author Simonato, Mauro Author Watson, Gillian W. Author Martinez-Sañudo, Isabel Author Tanaka, Hirotaka Author Zhao, Jing Author Pellizzari, Giuseppina text Zootaxa 2016 4093 4 539 551 journal article 10.11646/zootaxa.4093.4.5 2f3bf67e-288b-4e6d-8819-878a6852c8be 1175-5326 264159 A88B7833-D381-468C-A230-A2CD6FF6611A Phenacoccus defectus Ferris, 1950 Phenacoccus defectus was described from specimens collected on Eriophyllum confertiflorum (Asteraceae) in California, Santa Clara County, Permanente Creek (Ferris 1950). Permanente Creek is just 3.2 miles from Palo Alto, the type locality of P. s o l an i . Phenacoccus defectus was subsequently recorded from several other localities in California (McKenzie 1967) and Mexico (Williams and Granara de Willink 1992). The first European record of P. defectus was from Great Britain in 1997, indoors, on Echeveria and other succulent plants (Malumphy 1997). In 2006 it was recorded from southern France (Germain & Matile Ferrero 2006) and from 2009 onward, Italy (Pellizzari & Porcelli 2013). In 2012 it was reported from the Ryukyu Islands of Japan (Tanaka & Uesato 2012). Phenacoccus defectus develops on plants belonging to the Asteraceae , Chenopodiaceae , Crassulaceae , Euphorbiaceae , Fabaceae , Hydrophyllaceae , Lamiaceae , Poaceae and Polygonaceae (García et al. 2016) . In Crassulaceae , it has been recorded on Aeonium arboreum , Crassula portulacea , Echeveria sp., E. craigiana , E. longissima , E. lurida , E. recurvata , E. sessiliflora , Sedum palmeri and Sempervivum tectorum (McKenzie 1967; Williams & Granara da Willink 1992; Malumphy 1997; Pellizzari & Porcelli 2013). The species is parthenogenetic and ovoviviparous (Malumphy 1997; Pellizzari & Porcelli 2013). Comparison of the host ranges of P. solani and P. defectus shows that they share the same host families (including Crassulaceae ) (Ji & Suh 2012) except for Hydrophyllaceae , on which only P. d ef e ct us has been recorded (McKenzie 1967). The aim of this study was to examine whether P. defectus and P. s ol an i are distinct species, and if so, to discover a reliable means of separating them. A morphological analysis of adult females of the two species was performed to see whether these nominal species form separate populations, and to identify any consistent morphological differences between them. Williams & Granara de Willink (1992) used circulus size and shape, and the number of antennal segments to help separate P. solenopsis from P. solani , but Hodgson et al. (2008) found that both these characters were too variable to be reliable for diagnosis. Neither of these unreliable characters have been used in the past to distinguish between P. defectus and P. solani , so they were not used in this analysis. A molecular analysis using the mitochondrial COI and nuclear 28S genes was carried out on specimens from different parts of the world to determine whether P. defectus and P. solani are distinct species.