Acanthococcus aceris Signoret, 1875

Gavrilov-Zimin, I. A. & Kurochkin, A. S., 2019, Millennial zoological mystery of medieval Persian scientists, Zoosystematica Rossica (China) 28 (2), pp. 201-227 : 212-215

Acanthococcus aceris Signoret, 1875

(Fig. 11)

Signoret, 1875: 35; Cockerell, 1896: 323 ( Eriococcus ); Borchsenius, 1949: 347 ( Acanthococcus ); Schmutterer, 1952: 416 ( Eriococcus ); Kosztarab & Kozár, 1988: 278 ( Acanthococcus ); Kozár et al., 2013: 262 ( Acanthococcus ).

= Acanthococcus melnikensis ( Hodgson & Trencheva, 2008: 12, as Eriococcus ); Gavrilov, 2010: 38 ( Acanthococcus , synonymisation); Kozár et al., 2013: 134 (unsubstantiated disputing of synonymy).

Material examined. Germany: on Acer campestris (without other collecting data), 2 females . Bulgaria: 10 km S of Kiustendil, on Quercus sp. , 22. VI.2008 (I. Gavrilov leg.) 1 female . Poland: Krakow , on Quercus rubra , 29.IX.1966 (E. Danzig leg.), 4 females ; unclear locality, on Acer platanoides , 15. V.1967 (J. Koteja leg.), 4 females. Ukraine: Zakarpatskaia Prov.: near Nevitskoe Settlm. , on Acer tatarica , 16. VI.1956 (N. Borchsenius leg.), 3 females ; near Uzhgorod , on Acer sp. , 18. VI.1956 (N. Borchsenius leg.), 4 females ; near Uzhgorod, Latoritsa Riv. , 19. VI.1956 (N. Borchsenius leg.), 3 females . Russia: Krasnodar Terr.: Sochi, Agur Riv. Gorge , on Acer campestre , 16. V.2003 (I. Gavrilov leg.) ; Karachay-Cherkess Republic : 10 km S of Arkhyz Vill., 1600 m altitude, on Acer sp. , 4.VII.1976 (E. Danzig leg.), 2 females ; Dagestan: 15 km SW of Sergokaly , on Acer sp. , 16.VII.1983 (E. Danzig leg.), 8 females ; Primorsk Terr.: Vladivostok , on Acer mono , 2. VI.1963 (E. Danzig leg.), 1 female .

Dried colonies of females from Austria, Poland, Ukraine, Russia, and Georgia. Three series of females fixed in ethanol from Bulgaria and Russia (North Caucasus).

Morphological description. Adult female. Body egg-shaped, up to 3 mm long, intense red in life, located inside of white-grey wax sac which totally covers female and oviposited eggs. Antennae 6–7-segmented, each about 300 µm long. Legs with all segments normally developed, without translucent pores; claw with denticle; claw digitules with clavate apices. Anal apparatus with outer row of spinulae, incomplete inner row of pores and eight long setae, each about two times as long as diameter of anal ring. Multilocular pores absent. Quinquelocular pores (occasionally 6- or 7-locular pores), each about 5 µm in diameter, scattered on all ventral surface of body, excluding marginal zone of ventral head, thorax and anterior abdominal sternites. Oval discoidal pores (“cruciform pores” in some authors) each about 3 µm in diameter, forming marginal band on ventral head, thorax and anterior abdominal sternites. Macrotubular ducts of three sizes: larger ducts, each about 25 µm long and 8 µm wide forming transverse rows on dorsum; mid-sized ducts each about 20 µm long and 5–7 µm wide, forming marginal band on venter and occasionally present in medial-submedial zones of posterior abdominal sternites; smaller macrotubular ducts, each about 15 µm long and 2–3 µm wide, forming transverse rows on II–VII abdominal sternites. Microtubular ducts each about 8 µm long and 1 µm wide, scattered on all dorsal surface of body. Conical setae with more or less blunt apices, each about 15–20 µm long, forming transverse rows or bands on tergites and band along margin of dorsum; largest conical setae (each about 30–50 µm long) forming row (with 3–4 setae on each side of each segment) along body margin. Flagellate setae of different sizes forming transverse rows on abdominal sternites and sparsely present on ventral surface of thorax and head.

Morphology of larvae of both sexes and adult males was described by Hodgson & Trencheva (2008).

Fig. 11. General morphology of Acanthococcus aceris ( Russia: Karachay-Cherkess Republic).

Taxonomic notes. Gavrilov (2010: 38) considered in detail the absence of any discrete characters for separation of A. melnikensis from wellknown and widely distributed A. aceris :

“Recently, a new species Eriococcus melnikensis Hodgson & Trencheva (2008) , similar to A. aceris , was described from Bulgaria. Unfortunately, the diagnosis of the new species in the original description did not include a comparison of the adult females with those of A. aceris . Moreover, the description of A. aceris in Hodgson & Trencheva (2008) is very brief in comparison with huge description of the new species and was based on the short description by Williams (1985) and several females collected from one population in Padova ( Italy). The two characters used by Hodgson & Trencheva (2008) for the separation of these two species were included in the key only (p. 37, l.c.). These two characters were:

1) A. aceris , in contrast to A. (Eriococcus) melnikensis , has setae on antennal segment III. However, there is no enlargement of the antennae in the figure of A. aceris (Fig. 11, page 29, in Hodgson & Trencheva). Based on material preserved in Zoological Institute, St. Petersburg, and on descriptions by Borchsenius (1949) and Williams (1985), A. aceris can have 6- or 7-segmented antennae. When a female has 6 segments, segment III is rather long and bears 2 or 3 setae on its distal part. However, segment III is often more or less divided in two parts and then the new! segment III has no setae, because these remain on the new segment IV. It is well known, that the division or fusion of antennal segments often occurs in scale insects and sometimes a female can have different numbers of segments on two her antennae.

2) A. melnikensis has “ventral medium-sized macrotubular ducts only present submarginally, mainly on head and posterior abdominal segments” in contrast to A. aceris , which has “ventral medium-sized macrotubular ducts present medially on most abdominal segments”. However, in the figure ( Fig. 7, p. 18, l.c.), only two sizes of ducts are enlarged. Moreover, the description of the new species does not include the size of these ducts; it is written (p. 14) that they are “slightly smaller” than the large ones. In the description of A. aceris (p. 28, l.c.), the sizes of the ducts are not mentioned at all.

In the description of A. aceris by Williams (1985), the medium-sized ducts are “... not numerous [and are present], in more or less single rows on abdominal segments and around submargins to head”. So, there is no significant difference in this character even in the descriptions of A. aceris and A. melnikensis . Based on a study of material [in the collection of Zoological Institute] in St Petersburg of A. aceris from different localities, these two species appear to be identical. Unfortunately, this is not surprising because the distribution and number of ducts (or pores) varies very significantly in many scale insect species, especially in widely distributed common species, such as A. aceris Signoret.

Differences were also noted by Hodgson & Trencheva (2008) between first-instar larvae of these two species – in particular, the size and form of the spinose setae. These differences were based on a study of 3 larvae from one population of each species. As the variation of morphological characters in the larvae of scale insects has not been well studied, it is not known what the differences between larvae from different localities, different host plants, etc are likely to be significant. Until there is a clearer understanding of this variation, their taxonomic significance is unknown. Therefore, based on the above mentioned comments, I consider that A. melnikensis is a new junior synonym of A. aceris .”

Kozár et al. (2013: 83) tried to dispute this synonymy without providing any counterarguments, but with only the writing of the naive statement: “there are big differences between first instar nymphs of A. aceris and A. melnikensis which clearly belongs to the Acanthococcus roboris group. On this base we reestablished here A. melnikensis species status”.

Thus, any reader can clearly see and compare here two different approaches to the discussed taxonomic problem.

Ontogenesis and mode of life. The ontogenesis is similar with other species, discussed here (Fig. 9). The reproduction is bisexual; females lay each 82– 378 eggs; primolarvae hatch in about 30–35 days after oviposition ( Schmutterer, 1952); overwintering as a secundolarva ( Kosztarab & Kozár, 1988).

The species mainly inhabits trunks and branches of Acer spp. , more rarely Aesculus spp. , Quercus spp. , Fagus spp. and some other forest trees. The record of willow ( Salix caprea ) as a host plant of this species ( Kozár et al., 2013) is probably a mistake, copied from ScaleNet (E. Szita, personal communication). Females usually do not form large colonies or even separate females are located far from each other on the host plant.

Distribution. The species is widely distributed in Europe, Transcaucasia and in the Near East; its presence in Iran ( Moghaddam, 2018) was based on a student’s note and needs additional checking (M. Moghaddam, personal communication).