Two more new species of Aphidura (Hemiptera, Aphididae), and a note on variation in Aphidura bozhkoae Narzikulov

Abstract Two new species of Aphidura Hille Ris Lambers, 1956 (Hemiptera, Aphididae, Macrosiphini) are described; Aphidura libanensis sp. n. from Prunus prostrata in Lebanon, and Aphidura corsicensis sp. n. from Cerastium soleirolii in Corsica (France). Studies of Aphidura bozhkoae specimens from different localities have revealed that this species varies in its pattern of dorsal sclerotisation and other morphological characters, within and between populations. An updated key for identifying the world’s species of Aphidura is presented.


Introduction
Aphidura Hille Ris Lambers, 1956 (Hemiptera, Aphididae, Macrosiphini) currently includes 22-25 subjective valid species, exhibiting a Mediterranean-Pontian-Turanian distribution with extensions to neighbouring areas and exceptionally (one species) to the Russian Far East. Many of the species are associated with Caryophyllaceae, and some feed on Prunus and related genera, indicating that there may be host alternation between Amygdaloideae (Rosaceae) and Caryophyllaceae, but their biology and life cycles are mostly unknown (Blackman and Eastop 2014). Twelve of the species were described in 2013 (Kadyrbekov 2013;Nieto Nafría et al. 2013), adding greatly to the knowledge of the genus. Two more species were present among specimens conserved in the collection of the Natural History Museum in London (BMNH), and they are described in this paper.
Aphidura bozhkoae Narzikulov, 1958 was described from Prunus (= Cerasus) verrucosa in Tajikistan, and has subsequently been found on various species of Prunus in the neighbouring countries Kyrgyzstan and Uzbekistan, and also in Kazakhstan, Iran and Georgia . The variation in several morphological features exhibited by this species, both within and between populations, is remarkable. In particular, Iranian specimens (illustrated by Nieto Nafría et al. 2013: 10, fig 3A) differ from the Tajik type series (illustrated by Narzikulov 1958: 16, fig. 1) to such an extent that D. Hille Ris Lambers gave them the specific epithet "nitens", which was however never published. The variable characters include those that have been used to discriminate between other species of Aphidura, some of which are described from only single collections, so for future work on this genus it is important that the variation in A. bozhkoae should be reviewed and discussed.
A Leica DC digital 96 camera with IM 1000 version 1.10 software was used for the photomicrographs, which have been taken and mounted by L. M. Fernández Blanco.

Descriptions of new species
Aphidura libanensis sp. n. http://zoobank.org/ECE4A97D-D03F-45CA-BEB5-57C64853ED30 Diagnosis. Siphunculi tapering to apex or slightly swollen in a distal portion. Dorsum of metathorax to abdominal segment 6 with a discal plate (apterae). Mesosternal mammariform processes pale, flat and with spinules (apterae). Abdominal marginal tubercles usually present. Tarsal formula 3.3.3. (sometimes one tarsus with 4 setae) Apterous viviparous female, from 5 specimens (Figs 1A-E). Unknown colour in life, possibly shiny black with antennae, legs and siphunculi pale brown. In mounted specimens, antennae, mesosternal mammariform processes, legs, siphunculi, abdominal segment 8 sclerotized band, cauda and genital and anal plates are yellowish brown, with very proximal and distal portions of siphunculi, antennal segment VI and very apical portion of antennal segment V somewhat darker than aforementioned structures, all in contrast with head and dorsum of thorax and most part of abdomen, which are very dark brown. Frons undulated. Head with rugosity lines and spinules (both more abundant on dorsum). Antennal cuticle imbricated. Setae on body dorsum, antennae, and most of those on legs thick, with apices blunt or slightly capitate. Mesosternal mammariform processes pale, flat and with spinules. A discal plate present (from metathorax to abdominal segment 6); prothorax, mesothorax and abdominal segment 7 with wide transverse bands, which are darker than the discal plate, abdominal segment 8 with a band paler than the others. Marginal tubercles usually present on both sides of prothorax and several abdominal segments; they are small, but the abdominal ones are relatively tall. Siphunculi tapering to apex or slightly swollen in the distal quarter, spinulose imbrication, distinct preapical incision and flange. Cauda broadly triangular. Metric and meristic features in Table 1.
Etymology. The specific name of the new species is an adjective that means inhabitant of Lebanon, in feminine.  Discussion. D. Hille Ris Lambers thought that these Lebanese specimens were conspecific with others found on Prunus in Iran, which were being studied by him and G. Remaudière, and that they all belonged to an undescribed species, which was named in draft "nitens" (Remaudière's epistolary archive). Certainly these Lebanese aphids do not belong to any previously described species, but they are also not conspecific with the Iranian ones, which we believe to be A. bozhkoae (see next section).
Aphidura libanensis sp. n. resembles Iranian specimens of A. bozhkoae and the East Asian species A. mordvilkoi in the shape of the siphunculi and the extensive and solid discal plate, but there is an important difference in the number of first tarsal setae: four setae on each first tarsal segment in A. bozhkoae and A. mordvilkoi , and three in A. libanensis. A. libanensis and A. mordvilkoi can also be distinguished from one another by the number of accessory setae on the ultimate rostral segment (6-9 in A. libanensis, 2-4 in A. mordvilkoi) and the relative length of the processus terminalis (3.6-4.9 times base of antennal segment VI in A. libanensis, 2.2-2.7 times in A. mordvilkoi). A. libanensis and A. bozhkoae are very similar in absolute and relative lengths of most body parts, the setae of A. libanensis (Table 1) are all generally longer than those of A. bozhkoae (Table 2). Aphidura corsicensis sp. n. http://zoobank.org/EA353AA4-B640-4294-A9B0-8A7C58C546CB Diagnosis. Siphunculi slightly swollen. Dorsum of thorax and abdomen with setiferous sclerites (apterae). Mesosternal mammariform processes pale, flat and smooth (apterae). Abdominal marginal tubercles absent. Tarsal formula 3.3.3 Apterous viviparous female, from 3 specimens (Fig. 2). Shiny dark green in life. In mounted specimens, head, antennae, legs, siphunculi, cauda, genital and anal plates, and thoracic and abdominal sclerites yellowish brown, with apex of antennal segments III, IV and V, antennal segment VI, very apex of tibiae, tarsi and apex of siphunculi something darker than aforementioned structures. Frons undulated. Head mostly smooth, some rugosity lines are present on dorsum. Proximal section of anten- nal segment III and segments IV-VI imbricated. Setae on body dorsum, antennae and most of those on legs thick with apices blunt or slightly capitate. Mesosternal mammariform processes pale, flat and smooth. Setiferous sclerites present on dorsum of thorax and abdomen, mostly with one setae and similar in size to spiracular sclerites; marginal sclerites on abdominal segments 2-4 often coalescent; those on segment 6 forming postsiphuncular sclerites; and those on segment 7 and 8 partially coalescent;  Etymology. The specific name of the new species is an adjective that means inhabitant of Corsica, in feminine.
Discussion. This species was included as Aphidura sp. in the host lists and key to aphids on Cerastium by Blackman and Eastop (2006), but has not previously been formally described.
Aphidura corsicensis can be easily distinguished from other Aphidura species by the abundant dorsal setiferous sclerites, which are not present in any other species of the genus. The host plant is not normally found below 1900m (Arthur Chater, Kew Gardens, pers. comm.) but the plant hosting A. corsicensis was estimated to have been collected at around 1100-1200m (Martin). Narzikulov (1958) described Aphidura bozhkoae as a shiny black aphid with black siphunculi feeding on Cerasus verrucosa (currently in Prunus) in Tajikistan. His illustration ( Fig. 1 on p.16) depicts an aptera with extensive dorsal sclerotisation, but the metanotal sclerite is separate from the abdominal discal plate and has a mesial gap. In specimens from the type series in the BMNH collection this gap is quite wide and coincides with an indentation of the anterior part of the abdominal discal plate, to form a conspicuous irregularly-shaped window. All these specimens have siphunculi as dark as or darker than the discal plate. In contrast, specimens from Iran in the BMNH collection all have the metanotal sclerite forming a broad band fused with the abdominal discal plate. so that the sclerotisation extends as a solid shield from metonotum to abdominal tergite 6. Furthermore, these apterae have pale siphunculi. Another difference between Tajik and Iranian specimens in the BMNH collection concerns the mesosternal processes, which are well developed and well separated from each other in Tajik apterae, but much lower and more rounded in the specimens from Iran. These last features, all of them, are also shown by the specimen in Fig. 2A of Nieto Nafría et al. 2013).

The variability of Aphidura bozhkoae Narzikulov
In addition, the Tajik specimens all lack marginal or spinal tubercles, whereas in specimens from Iran small marginal tubercles may be present on some of abdominal tergites 2-6, and there may also be spinal tubercles on abdominal tergite 8 (Table 1).
When morphometric data are compared, however, the ranges of measurements and ratios for all characters agree well between countries, any slight differences being within the expected range of intraspecific variation (Table 2). Furthermore, examination of more Tajik material from the Zoologicheskiy Institut collection (Figs 3, 4), and of more apterae from Iran in the collection of the Muséum national d'Histoire naturelle, showed that the BMNH specimens constituted the extremes of a range of variation in a single species, with Iranian apterae in particular varying in the dorsal pattern of sclerotisation, pigmentation of siphunculi and shape of mesosternal processes. Further confirmation came from photomicrographs of A. bozhkoae from Prunus incana in Georgia kindly provided by S. Bardjadze, which showed a similar range of variation in these characters within a single sample.
Intraspecific variation in the extent of dorsal sclerotisation is evident in other species of Aphidura, especially in those that are widely collected such as A. picta. However this usually involves varying degrees of fragmentation or reduction of the entire discal plate rather than any specific part of it; in this respect the variation shown by A. bozhkoae is unusual. Siphuncular pigmentation and the extent of development of the mesosternal processes are characters that have been used to discriminate between Aphidura species, but experience with A. bozhkoae shows that they need to be applied carefully, especially when describing new species from small samples. Siphunculi pale, sometimes with smoky apex, 1.6-2.2 times cauda, which has 6-7 setae. If a spino-pleural patch present then ultimate rostral segment is 1.