Myzocallis, Passerini, 1860

Barbagallo, Sebastiano & Massimino Cocuzza, Giuseppe E., 2022, Description of a new Myzocallis (Hemiptera Aphididae) living on Valonia oak in Southern Italy with DNA barcoding accounts on allied species-group, Zootaxa 5183 (1), pp. 187-202 : 200-201

Key to species. The present key may help to separate alate fundatrigeniae (except where otherwise quoted) of the five oak-living aphid species belonging to subgenus Myzocallis .

Further accounts can be supplied from Quednau & Remaudière (1994), Quednau (1999) and Blackman & Eastop (2021). Additional biometric data are reported in Tab. 4 .

1. Viviparous morphs both alatae and apterae.Abdominal spinal sclerifications, when present (they occasionally lack in some pale apterous specimens), usually coalescing along their median line on urotergites 4 th and 5 th (or 4 th –7 th in apterae). Last rostral joint acute-conical; its ratio to 2 nd hind tarsomer (urj/IIht) 1.16–1.30 in alatae, 1.26–1.45 in apterous viviparous morph. Apterae and their 4 th instar nymphs with dorsal body hairs strongly capitate: i.e. distal knobs of spinal hairs on 1 st –5 th urites mostly larger (up to 1.4–1.9) than the basal width of the same hairs. Embryos with spinal hairs on 2 nd –4 th segment from 0.7–0.9 up to 1.00–1.25 (on 4 th urite) times their basal distance on the same segment. On Q. ithaburensis and Q. persica in the Middle East ( Israel, Iran, Turkey)................................................................... M. glandulosa Hille Ris Lambers

- All viviparous alatae, with abdominal spinal sclerifications always well separated along the median line on all urotergites. Ratio urj/IIht 0.90–2.10. Alatoid nymphs with dorsal body hairs having comparatively smaller knobs and embryos with spinal hairs on 2 nd –4 th abdominal segment varying from about 0.50 to 1.95 of their basal distance on the same segment. On other oak species.............................................................................................. 2

2. Last rostral joint narrow and stiletto-shaped, 0.15–0.22 mm long, with nearby parallel sides for most of its length and 4–5 times longer than wide at base; its ratio to 2 nd hind tarsomer (urj/IIht) 1.50–2.10 (but only rarely less than 1.60). Ratio urj/VIb 1.25–1.70. Embryos with spinal hairs on 2 nd –4 th abdominal segments (mainly the pair on 4 th urite) usually longer (1.25–1.95) than their basal distance on the same segment. Holocyclic on Q. pyrenaica in SW. Europe ( France, Spain, Portugal)........................................................................ M. occidentalis Remaudière & Nieto Nafria

- Last rostral joint acute conical 0.090 –0.155 mm and not longer than 4 times of its basal width (seen from a normal dorso-ventral position); its ratio to 2 nd hind tarsomer 0.90–1.60. Ratio urj/VIb 0.70–1.25. Embryos with spinal hairs on 2 nd –4 th abdominal segments 0.50–1.70 of the distance between their bases. On different oak species................................... 3

3. Last rostral joint 0.110 –0.155 mm (up to 1.60 in fundatrix) and ratio urj/IIht 1.36–1.60. Ratio urj/VIb 0.95–1.25. Dorsal body hairs (i.e. discals on head, thorax and 1 st –5 th abdominal segments) capitate, subcapitate or at least blunt at apex, and ranging (12)16–52 µm in length. Alatoid nymphs with dorsal body hairs, as above quoted (couplet 1.) well capitate, with distal knobs mostly from subequal to wider (0.9–1.3) in diameter than the basal width of the same hairs. Embryos with spinal hairs on 2 nd –4 th abdominal segments 0.90–1.70 (1.15–1.70 on 4 th urite) of distance between their bases. On Q. macrolepidis ; so far only known from S. Italy (Apulia region)........................................................... M. macrolepidis sp. n.

- Last rostral joint 0.090 –0.132 mm long (up to 0.135 in fundatrix of M. boerneri ) and ratio urj/IIht 0.90–1.45. Ratio urj/VIb 0.70–1.10. Dorsal body hairs as above quoted, either all acute and 14–22 µm long ( M. schreiberi ) or variable at apex from rather acute to subcapitate or capitate and usually ranging 10–30 µm (occasionally up to 32–38 µm). Alatoid nymphs with dorsal body hairs (namely on 1 st –5 th urites) moderately capitate, i.e.: knobs diameter mostly subequal or smaller (0.8–1.1) than the basal width of the same hairs. Embryos with spinal hairs on 2 nd –4 th urites (0.50–1.20 higher values refer to hairs on 4 th urite) of their basal distance........................................................................................ 4

4. Last rostral joint 0.094 –0.132 mm long and ratio urj/IIht 1.18–1.45 (most frequently 1.20–1.35). Dorsal body hairs (head, thorax and abdominal segments anterior to siphunculi) all short (14–22 µm long) and acute at apex. An anholocyclic taxon living on evergreen oaks, such as Q. ilex , Q. suber , Q. x crenata in W. Europe and the Mediterranean...................................................................................... M. schreiberi Hille Ris Lambers & Stroyan

- Last rostral joint 0.090 –0.125 mm (0.115 –0.135 mm in fundatrix), and ratio urj/IIht (0.84)0.90–1.25 (up to 130 in fundatrix and 2 nd spring generation of viviparous alatae). Dorsal body hairs variable in length and shape from rather acute or blunt, (10)14–26 µm (prevailing in summer generations), to subcapitate or capitate ones, 28–38 µm long (mainly in fundatrix and early spring generations). A holocyclic species usually common on Q. cerris , though also living on a number of additional oak species.

Widespread from SW. Europe and the Mediterranean eastward to the Middle East, also introduced outside its native area........................................................................................ M. boerneri Stroyan