Morphology of the first-instar nymph and adult female of Kermes echinatus Balachowsky, with a comparison to K. vermilio Planchon (Hemiptera, Coccoidea, Kermesidae)

Abstract Thefirst-instar nymph and the adult female of Kermes echinatus Balachowsky (Hemiptera, Coccoidea, Kermesidae) are described and illustrated. This species is compared with Kermes vermilio Planchon, a morphologically similar species known in the Palaeractic region.


Introduction
The scale insect family Kermesidae (Hemiptera, Coccoidea) develops and feeds exclusively on Fagaceae trees (Ben-Dov et al. 2012). This scale insect family is composed of one hundred species distributed among ten genera and they are currently known from the Nearctic, Oriental and Palaearctic regions of the world. Kermes Boitard is the principal genus in the European and Mediterranean regions. In these regions, twenty species of Kermes have been recorded, all off deciduous and evergreen oak trees (Quercus) (Ben-Dov et al. 2012). Individual insects develop mainly in bark crevices and on small twigs and branches (Sternlicht 1969, Bullington and Kosztarab 1985, Hu 1986, Podsiadlo 2005a). Most Kermesidae are not known to cause any visible injury to their host trees. There are however some reports of heavy infestations that can lead to branch dieback, flagging, reduced growth rates and occasionally tree death (Kozár 1974, Hamon 1977, Solomon et al. 1980, Viggiani 1991, Pellizzari et al. 2012. Seven Kermesidae species, belonging to two genera, Kermes Boitard and Nidularia Targioni Tozzetti, have been described or recorded from Israel off Quercus sp. (Ben-Dov et al. 2012). Two species: K. greeni and K. nahalali, were described from the postreproductive adult female (Bodenheimer 1931); three species: K. echinatus, K. palestiniensis and K. spatulatus, were described from first-instar nymphs (Balachowsky 1953); one species, K. bytinskii, was described from the adult female and all nymphal instars by Sternlicht (1969). The adult female of Nidularia balachowskii was described from Turkey (Bodenheimer 1941) and later was recovered in Israel (Bodenheimer 1944).
Kermes echinatus Balachowsky is one of six Kermes species found in Israel (Ben-Dov et al. 2012). To date, this species has only been reported off the evergreen oak, Quercus coccifera L., from one location in the Lower Galilee in Israel. Some scale insects have been known as sources of red dye used in the textile, art and wine industries in the Mediterranean, Middle East and Central Asia regions (Leonardi 1920, Donkin 1977, Sarkisov 1984, Cardon 2007) for many centuries. Scholars have suggested that the red dye used for both secular and ritual purposes in Israel during ancient times apparently had been imported from neighboring countries where such dye producing scale insects as Porphyrophora hameli Brandt and Kermes vermilio Planchon are known (Sandberg 1997). However, Amar et al. (2005) extracted red dye from both the adult females and eggs of K. echinatus and chemically analyzed it and suggested that K. echinatus might be the "Tolaat Shani" (scarlet worm in Hebrew), an animal mentioned in the bible used for dye extraction during the period of the second Holy Temple Period (70 A.D.) in Israel. Balachowsky (1953) described and illustrated the morphology of the first-instar nymph of K. echinatus from specimens that were collected off Q. coccifera from Nahalal forest located in the Lower Galilee in Israel. He also provided a brief description of the adult female, which included its color, shape and body dimensions. He compared the morphology of K. echinatus with the first-instar nymph of K. vermilio, another Palaearctic Kermes species not present in Israel, and concluded that "both species share general topography and structure of characters… therefore K. echinatus is the eastern neighbor of K. vermilio".
The first-instar of both K. echinatus and K. vermilio are easily distinguishable from other Mediterranean and European Kermes species due to the presence of conical, spine-like marginal setae (Balachowsky 1953, Pellizzari et al. 2012). The first-instars of other Palaearctic Kermes species possess hair-like, spatulate or club-shaped marginal se-tae (Kuwana 1931, Balachowsky 1950, Sternlicht 1969, Hu 1986, Liu and Shi 1995, Podsiadlo 2005b. To date there has been no detailed taxonomic description of the adult female of K. echinatus. This study presents a description of the adult female and a redescription of the first-instar nymph of K. echinatus. We also compare the general appearance and morphology of both stages with K. vermilio.

Specimen collections
Between 2010 and 2012, we collected specimens of K. echinatus off the evergreen oak, Q. calliprinos Webb, from forests in the Golan Heights, the Western, Upper and Lower Galilee regions and the Judean Mountains in Israel. The collection site at Timrat in the Lower Galilee is three km from Nahalal, the type locality of K. echinatus, and therefore we consider these specimens to be topotypic material. Some of the first-instar nymphs examined in this study emerged from females that were kept in sealed glass containers in the laboratory and other specimens were recovered from thin branches or from trunks of trees.

Identification and morphological observations
Specimens were processed and mounted on microscope slides according to the methods outlined by Ben-Dov and Hodgson (1997). Illustrations of the adult female and the first-instar nymph of K. echinatus are generalizations of several specimens, showing the dorsum on the left and the venter on the right, with enlargements of important structures arranged around the central drawing. The structures are not drawn to the same scale between each other. Terms for morphological features follow, chiefly those of Bullington and Kosztarab (1985), Baer and Kosztarab (1985) and Hodgson (1994). Measurements of specimens and of morphological structures were made using an ocular micrometer on an Olympus BX51 phase contrast microscope. Measurements of structures are given in millimeters (mm) or microns (µm). Body length was measured from the farthest points of the head to the posterior end of the body and body width was the greatest width. Setal lengths were measured from the base of the seta to the apex, i.e. excluding the setal socket. Fresh topotypic specimens collected by us in Israel plus one syntypic first-instar nymph were used for the descriptions. The frequency of each structure is given for the entire body. The range is taken from twenty specimens.

Discussion
Prior to this study, K. echinatus had only been reported off the evergreen oak, Q. coccifera, from Nahalal forest, located in the Lower Galilee of Israel (Balachowsky 1953). During the 2010 to 2012 surveys of Kermesidae throughout the country, specimens were recovered off Q. calliprinos trees in the Golan Heights, Western, Upper and Lower Galilee regions, as well as the Judean Mountains. It is widely accepted by botanists that Q. calliprinos is probably an East Mediterranean subspecies of, or a vicariad species to, Q. coccifera, which is distributed in the Mediterranean territories of Europe (Zohary 1973, Jalas andSuominen 1976).
The present description of the first-instar nymph of K. echinatus agrees well with that of Balachowsky (1953). However our redescription includes several features that were not indicated in the original description but were observed by in us in fresh and type material. These features are the presence of: (i) dorsal submedial setae; (ii) ventral bilocular pores; (iii) a claw denticle on each leg; (iv) and microspines dispersed on thoracic and abdominal regions. Balachowsky (1953) observed two main differences between the morphology of the first-instar nymph of K. echinatus and K. vermilio: (i) dorsal simple pores present on K. echinatus but absent on K. vermilio and (ii) the structure and arrangement of the marginal conical setae. In K. echinatus, the conical marginal setae are slightly longer and curved compared to those of K. vermilio. Balachowsky considered that the marginal setae of K. vermilio were of one length and arranged in two rows while those of K. echinatus were arranged in one row, but we found that first-instar K. echinatus also had two rows of conical marginal setae but that they differed in size and shape.
In addition, we observed other distinguishing features between the two species and these are summarized in Table 1. Pellizzari et al. (2012) added that the living specimens of K. vermilio are orange-red with yellow legs, whereas we noted that the firstinstar nymphs of K. echinatus are red. We also noted a small denticle on each claw of K. echinatus. These were considered to be absent on K. vermilio by Balachowsky (1950) and Pellizzari et al. (2012).
The general appearance of young females and fully-grown reproductive females of K. echinatus differs from that of K. vermilio. The young female of K. echinatus is slightly convex, has a brownish-grey dorsum with 4 or 5 black longitudinal and 6-9 black transverse lines composed of dots and lines. The young female of K. vermilio is reddish without transverse and longitudinal lines. The fully-grown reproductive female of K. vermilio has been described as dark red or brown covered with a fine, white or pale grey mealy wax (Pellizzari et al. 2012). In contrast, the fully-grown female of K. echinatus is not covered in wax and has transverse and longitudinal black lines on its dorsum. Both species at this stage are highly convex and subspherical.
The morphological features of the adult female of K. echinatus and K. vermilio are similar and are summarized in Table 2. Some of the shared features are the following; (i) dorsal and marginal conical setae; (ii) absence of legs; (iii) presence of numerous multilocular pores on abdominal segments as well as surrounding the antennae and spiracles; (iv) one-segmented antennae with fleshy setae; and (v) the anal ring located ventrally in both species. The most distinguishing feature of K. echinatus is the anal ring which has six setae and no cells whereas the anal ring of K. vermilio has cells but no setae. Some other differences between the two species are that K. echinatus has less conical setae on its margins and dorsum compared to K. vermilio. Kermes echinatus has 30-38 setae on each half margin compared to 73 -133 in K. vermilio. Kermes echinatus has 7-11 dorsal setae compared to about 70 dorsal setae in K. vermilio. Ventral loculate pores are only found on the abdominal segments and surrounding the spiracles in K. echinatus in contrast to K. vermilio, where they extend onto the metathorax from the abdomen.