It is well established that an significant part of the biodiversity is as yet undescribed, but it is not well known that an important portion of new species established by professional or non-professional (amateur) taxonomists is based on specimens preserved in the collections of museums, universities and other scientific institutions (Winston, 1999; Fontaine et al., 2012). Such collections also include many species that are still undescribed (Blackman & Eastop, 2006).

Specimens of two samples in the aphid collection of the Natural History Museum in London (BMNH) belonging to genus Uroleucon Mordvilko, 1914 (Hem. Aphididae Aphidinae Macrosiphini) have been studied, one from Lebanon and another from Iran. The slides of both samples had been labelled as new species by D. Hille Ris Lambers, and one of them is mentioned by Blackman & Eastop (2006, page 229).

Uroleucon currently includes 235 valid species and several subspecies (Favret, 2013; Nieto Nafría & Pérez Hidalgo, 2013), being one the largest genera of the tribe Macrosiphini.

The studied samples do not have a distinctive number; one is from Lebanon and the other from Iran.

Lebanese sample: “Carthamus flavescens, Arec, 26-XI-1971, Talhouk leg. (nr. 39)”;14 apterous viviparous females, 4 alate viviparous females and 6 immature specimens. This sample is mentioned by Blackman & Eastop (2006 [2013], page 229) as Uroleucon sp. near jaceae. The locality of Arec is in the Bekaa valley.

Iranian sample: “Helichrysum sp., Demavend Village, 12-VI-1960, van den Bosch leg. (IR 132)”; 25 apterous viviparous females, 5 alate viviparous females and 22 immature specimens. This sample is not mentioned by Blackman and Eastop (op. cit.). We think that the locality “Demavend” is a misspelling for Damavand, a locality near Mount Damavand.

Measurements of the slide-mounted specimens were made according to Nieto Nafría & Mier Durante (1998) with an ocular micrometer. The measurements are lengths except when indicated that they are a width or diameter.

The photomicrographs were taken with a Leica DC digital camera with IM 1000 version 1.10 software.

The Lebanese specimens above mentioned have been identified as Uroleucon jaceae (Linnaeus, 1758). We do not put a subspecific name on these specimens, because the species is very variable and the subspecies are badly defined.

The specimens of the Iranian sample are different to the Lebanese specimens, mainly in the shape and ornamentation of the siphunculi. We consider that these aphids belong to a new species of the genus Uroleucon, subgenus Uromelan.

Uroleucon helichrysi sp. n

APTEROUS VIVIPAROUS FEMALES (Table 1, Fig. 1). From 39 apterous viviparous females. Metric and meristic features in Table 1. Colour in life unknown. When mounted mostly pale yellowish brown with striae on dorsum of thorax and abdomen. Marginal tubercles usually present in prothorax and abdominal segments 2-4; they are small, similar in size to neighbouring seta sockets. Setae thick and pale, most of them with blunt or evanescent apex. Head brown, and dorsally with very faint striae. Frontal sinus very deep and fronto-medial tubercle small or inconspicuous (Fig. 1A). Antennae brown to dark brown, usually with the proximal portion of segment III paler; proximal portion of segment III and most of IV delicately ornamented, segments V and VI imbricated. Secondary sensoria scattered on proximal 50-66% of segment III; they are circular, small and somewhat protuberant. Rostrum reaching hind coxae, dark brown; ultimate rostral segment triangular; proximal ones with spinules. Thorax with striate pale brown marginal sclerites in addition to the brown spinal and pleural setiferous scleroites. Coxae, distal 1/3-1/2 of femora, very proximal portion and distal 2/5-1/3 of tibiae, and tarsi dark brown. Abdomen with dorsal setiferous scleroites (Fig. 1B), with neighbouring scleroites on abdominal segment 7 and 8 sometimes coalescent; postsiphuncular and antesiphuncular (sometimes broken) patches; and spiracular sclerites small and usually paler than the setiferous scleroites; the intersegmental sclerites are inconspicuous. Siphunculi dark brown (Fig. 1C), cylindrical with enlarged base and curved outward, and without both preapical incision and flange; cells of the reticulate part very small (Fig. 1E); part proximal to reticulation densely covered with groups of spinules or scales. Genital plate light brown with brown spots. Anal plate similar in colour to cauda, which is lanceolate and as dark as siphunculi (Fig. 1D).

ALATE VIVIPAROUS FEMALES (Table 1, Fig. 2). From 9 alate viviparous females. Metric and meristic features in Table 1. Colour in life unknown; when mounted similar to apterae (Figs. 2A, 2B). Antennae brown to dark brown, usually with the proximal portion of segment III paler (Fig. 2C). Secondary sensoria (60-82) circular small and somewhat protuberant (Figs. 2C, 2D). Abdomen with dorsal setiferous sclerites (Fig. 2B). Siphunculi dark brown (Fig. 2B), similar to those of the apterae, without both preapical incision and flange. Cauda is lanceolate and as dark as siphunculi.

BIONOMICS. The only known host plant of the aphid is an unidentified species of Helichrysum (Asteraceae); the capacity of this aphid to colonize other composites is unknown.

DISTRIBUTION. The new species is only known from one Iranian locality, in Mazanderan province.

ETYMOLOGY. The specific name helichrysi is the genitive of the name of the host plant of the new aphid species.

TAXONOMIC DISCUSSION. The assignment of the species to genus Uroleucon and subgenus Uromelan Mordvilko, 1914 is unquestionable, given the characteristics described above.

The principal characters involved in the comparison of U. helichrysi sp. n. (this work) to other Palaearctic species of Uromelan (original descriptions) are the tarsal formula (5.5.5), the number of caudal setae (20-28), the size of the siphuncular cells and the presence of marginal tubercles on abdominal segments 2-4.

Most Palaearctic Uromelan species have 5 setae on the first tarsal segments, but only five of them have 20 or more caudal setae (Hille Ris Lambers, 1939; Miyazaki, 1971; Takahashi, 1962; Rezwani & Lampel, 1987; Heie, 1995; Lee et al., 2002): U. aeneum (Hille Ris Lambers, 1939), U. caspicum Rezwani & Lampel, 1987; U. cephalonopli (Takahashi, 1962), U. giganteum (Matsumura, 1918) and U. jaceae (Linnaeus, 1758).

U. caspicum and U. giganteum (Matsumura, 1918) have many more setae on the cauda than U. helichrysi (24-41 and 40-60 respectively). U. cephalonopli has, in comparison with U. helichrysi, a long and narrow ultimate rostral segment (0.22-0.30 mm and 1.4-1.6 times second segment of hind tarsus), and the siphunculi and cauda are different in shape (see Lee et al., 2002, fig. 227). U. jaceae lacks abdominal marginal tubercles, and the cells of the siphuncular reticulation are larger than those in U. helichrysi, as in U. aeneum. The metric and meristic characteristics of U. aeneum are very similar to those of the new species, but the shape and reticulation of the siphunculi are very different. In addition none of these species live on Helichrysum.

The “Key to apterae on Helichrysum” by Blackman & Eastop (2006, p. 510) can be modified to include U. helichrysi sp. n. as follows, respecting terminology, abbreviations and expressions.