Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 77. (Budapest 1985)

Vásárhelyi, T.: Investigations on the allometric growth of Aradus species (Heteroptera, Aradidae)

Table 2. Antennái formula in different developmental stadia of 8 Aradus species and of Oeciacus hirundinis u L L t L L í Adult betulinus 13:22:19:46 15 27 21 37 15 31 21 33 14 34 23 29 14 38 23 25 12 44 25 19 cinnamomeus 20:20:20:40 18 21 18 43 19 21 21 40 19 24 21 36 18 27 23 32 16 31 25 28 corticalis

1 — 16 25 19 40 18 29 20 33 15 34 22 29 14 38 24 24 12 44 25 19 corticalis

2 — 15 24 20 41 15 •28 21 36 14 33 22 31 13 38 23 26 11 45 24 20 krueperi — 15 30 20 35 14 36 21 29 13 42 20 25 11 :49 19 21 lauri — 19 21 23 37 15 •22 26 37 17 23 29 31 15 24 31 31 14 •25 35 26 pictus — 17 24 21 38 15 :31 19 35 15 35 20 30 12 35 21 :25 11 47 21 21 ribauti 11:21:19:49 15 28 19 :39 15 30 18 37 13 35 21 31 12 40 21 27 11 :46 21 22 safavi 16 19 28 37 17 :18 29 36 17 18 33 32 14 19 38 29 14 :19 43 24 hirundis 7

:22:26:45 8 22 28 42 8 :27 28 37 7 30 :30 33 10 33 27 30 10 :34 28 28 'Alto Adige, Italy (TAMANINI 1956) — 2

Vihti, Finland belonging to the betulae-group of the subgenus Aradus. The adult values of 8 other species of this species group are marked by empty circles while the further Aradus species by filled circles. Even the graphic evaluation suggests the homogeneity within the species-group mentioned above and the heterogeneity of growth ratio or initial growth index or both within the genus. Encouraged by these, antennái formula, i. e. the ratio of antennái joints expressed as percentage of the total length of the antenna was used as one of the fundamental characters (VÁSÁRHELYI 1985) in a key constructed for the fifth instar larvae. The antennái formula is essentially a standardization of the data given by different authors in different scales for the relative length of the antenna! joints 1 to 4. Postembrional change of the antennái formula of several Aradus species was investigated (for examples see Table 2), of which three and that of a Cimicid species is graphically demonstrated (Figs. 7-10). In each case, in the first instar joint 4 was the longest amounting to almost half of the antenna. Joint 1 is generally the shortest and its relative length does net change strikingly in the subsequent stages. Either joint 2 or 3 grows more slowly, sometimes isometrically, and the other has a higher growth ratio to reach the imaginai proportions in most cases. A negative allometric growth characterizes joint 4 in each case. Less clearly but the same can be seen from comparison with head width (Table 1). Postembrional change in the antennái formula as well as the allometric growth of the antennái joints of the species investigated, when compared with e. g. width of head, provide valuable data in distinguishing the developmental stadia in elder larvae rather than in the first two instars. Here the thoracal structures also show valuable characters, however, they may not be useful in identifying the larval instars of the apterous Aradidae, many of which, contrary to the pertinent literature, do not have wing pads and exhibit yet unexplained features.