Dysaphis indica Chakrabarti & Medda, 1993

Stekolshchikov, Andrey V., 2014, Taxonomic notes on some species and subspecies of aphids (Hemiptera: Aphididae), Zootaxa 3760 (4), pp. 563-570 : 563-565

Dysaphis indica Chakrabarti & Medda, 1993 , new status

This aphid has previously been treated as a subspecies of Dysaphis pavlovskiana Narzikulov, 1957 . Chakrabarti and Medda (1993) described 53 apterous viviparous females collected from Sorbus in India (Uttar Pradesh, Garhwal Hills) as specimens of new subspecies— Dysaphis pavlovskiana indica . They noted that the new subspecies differs from the nominative taxon mainly in the lack of spines on the head, the greater length of the ultimate segment of rostrum, the slightly longer siphunculus and the fact that all the setae on the antennae were thin and pointed unlike those of the nominotypical subspecies, which has most of the setae on the antennae blunt or slightly capitate. Actually there is no description of the apterous vivipara in their paper, which only gives the differences listed above and measurements of several characters of the holotype. The authors also suggested that the seven alate and two apterous viviparous females and 30 nymphs which they collected on 16 September 1982 from Saussurea piptathera Edgew. (cited as Saussurea pipethera in their paper) in Uttar Pradesh (Garhwal Hills), as well as one alate female which they caught on 17 September 1982 on Rhamnus dahurica Pall. in Garhwal Hills refer to this subspecies. According to the authors the aphid was accidentally on Rhamnus dahurica . They also suggested that the alatae collected on Saussurea are gynoparae which should migrate to Sorbus . Indeed, judging by the description of alatae and apterous viviparous females from Saussurea piptathera given in the article and by the comparison of aphids from Sorbus and aphids from Saussurea made by the authors, these individuals all belong to one taxon.

Hitherto Dysaphis pavlovskiana , sensu stricto was known from Eastern and Western Siberia, Kazakhstan, Uzbekistan, Kyrgyzstan, Tajikistan and Pakistan ( Narzikulov 1957; Ivanovskaya, 1977; Gabrid, 1989; Kadyrbekov, 1990; Naumann-Etienne & Remaudière, 1995; Stekolshchikov & Shaposhnikov, 1998; Holman, 2009). Slides have now been studied of aphids collected by G. Remaudière on 17 June 1966 from Sorbus graeca (Lindl.) Fritsch & Rech. in Turkey (Konya, Ereğli) at an altitude of 2000 m above sea level and stored in the aphid collection of Muséum national d'Histoire naturelle.

This sample contains four fundatrices, eight apterae and 34 alate viviparous females. These aphids are very similar to D. pavlovskiana housed in the Russian collections in all characters, differing from them only by the greater length of the ultimate segment of the rostrum and its relation to the length of 2nd segment of hind tarsus, as well as having more long setae on the body and appendages. However, if we consider the variation in these characters in different populations of D. pavlovskiana ( Tabl. 1 ), we see that when going from north to south, not only the absolute length of the ultimate segment of the rostrum but its ratio to the length of 2nd segment of hind tarsus increases, and this phenomenon is more or less clearly expressed for all morphs for which it is possible to make a comparison. A similar, though less clearly expressed situation is observed with the length of setae. Individuals from Turkey are thus just an extreme variant on the line of these changes, conforming completely to this trend and undoubtedly belonging to the species D. pavlovskiana .

The situation is different with Dysaphis pavlovskiana indica Chakrabarti & Medda, 1993 . In indica the absolute length of the ultimate segment of the rostrum is greater than in pavlovskiana s.str., but the ratio of the length of the ultimate segment of the rostrum to the length of the second segment of hind tarsus does not differ ( Table 1 ). In addition, indica differs from pavlovskiana in the following characters (apart from those listed in the original description): body length ( indica longer), ratio of length of processus terminalis to length of base of last antennal segment (greater in indica , especially for the morph from Saussurea ), longer cauda (at least for morph from secondary host), number of rhinaria on the segments of antenna of gynoparae (more in indica ), and by some other characters (Table 2). Information about the length of setae of apterous females of indica from Sorbus is absent from the original description, but morphs of indica from the secondary host have longer setae than the respective morphs of pavlovskiana . However, as stated above, this character has no significant value in the taxonomy of this group. Apterous exules of pavlovskiana from Plantago are strongly sclerotized, with sclerotic bands from meso- or metathorax to VII abdominal tergite fused with marginal sclerites and forming a complete dorsal shield. Apterae of indica from Saussurea are almost unsclerotized, having only a sclerotized band on abdominal tergite VIII. The secondary host of indica is Saussurea , whereas pavlovskiana migrates from Sorbus to Plantago ( Shaposhnikov, 1974; Stekolshchikov & Shaposhnikov, 1998). These significant differences between indica and pavlovskiana in morphology and, more importantly, in biology (a different secondary host) indicate that it as a separate species— Dysaphis indica Chakrabarti & Medda, 1993 (new status).

D. indica is undoubtedly very closely related to D. pavlovskiana and they have a common ancestor that may have migrated from Sorbus in the second and third generation to a more-or-less wide range of secondary hosts. This ancestor had a long ultimate segment of the rostrum, long thin setae, slightly swollen or unswollen siphunculi, and strongly sclerotized apterous viviparous females on Sorbus and on secondary hosts. After separation D.indica apparently remained in a relatively narrow area within the Himalayas, while D. pavlovskiana became widespread in Eurasia—from Turkey to Eastern Siberia. As already pointed out ( Stekolshchikov & Shaposhnikov, 1998), the spread of D. pavlovskiana from south to north was accompanied by some changes in its morphology and, more importantly, in its biology; both emigrants and apterous viviparous females are among the offspring of the fundatrix in populations of Tajikistan and Turkey (in Tajikistan apterae are found on Sorbus until the 5th generation), but there are no apterae on Sorbus in the Kazakhstan and East Siberian populations, the fundatrix producing only alatae females—emigrants.

Tables

TABLE 1. Length of ultimate segment of rostrum and ratio of ultimate segment of rostrum to 2 nd segment of hind tarsus for different populations of Dysaphis pavlovskiana Narzikulov, 1957 and D. indica Chakrabarti & Medda, 1993.

	Dysaphis pavlovskiana Eastern Siberia Kazakhstan Tajikistan	Turkey	Dysaphis indica
Fundatrices Ultimate segment of rostrum	135–160 143–154 151–168 (135–146) (150) (157–161)	188–195 (192)	–
Ultimate segment of rostrum/ 2nd segment of hind tarsus	1.05–1.28 1.16–1.33 1.32–1.51 (1.11–1.19) (1.22) (1.44)	1.64–1.86 (1.77)	–
Apterous Ultimate segment of rostrum from Sorbus	– – 123–149 (135–142)	160–182 (173)	200–220
Ultimate segment of rostrum/ 2nd segment of hind tarsus	– – 0.94–1.17 (1.08–1.13)	1.18–1.50 (1.39)	1.33
Emigrants Ultimate segment of rostrum	115–140 107–135 123–151 (126–133) (126) (128–141)	155–176 (165)	–
Ultimate segment of rostrum/ 2nd segment of hind tarsus	0.84–1.02 0.83–1.04 1.00–1.23 (0.95) (0.96) (1.11)	1.38–1.59 (1.47)	–
Apterous Ultimate segment of rostrum exules	101–121 109–118 112–123 (113) (112) (116)	–	210–220
Ultimate segment of rostrum/ 2nd segment of hind tarsus	1.05–1.29 1.10–1.17 1.08–1.37 (1.11–1.18) (1.14) (1.21)	–	1.31–1.35
Gynoparae Ultimate segment of rostrum	– – 107–121 (114)	–	160 1
Ultimate segment of rostrum/ 2nd segment of hind tarsus	– – 1.00–1.24 (1.12)	–	1.13–1.14
1 — only one specimen.