The Roman Map of Britain Annis? Arnus?

Armis (R&C 42) next

Armis presents difficulties both in assignment and certainty of form, as -rmi- is essentially a series of five minim strokes, easily misread.

It may be on a road radiating from the previous entry Venta Belgarum (R&C 41). 
These roads are:
Margary 42b south toward Bitterne Clausentum
Margary 45a west toward Old Sarum, recorded in AI as Sorbiodunum,
Margary 42a northeast toward Silchester Calleva
Margary 420 southeast toward Wickham *Maiona
and an expected road eastward toward Neatham that remains uncharted.
Neatham (SU7441) on the River Wey

Alternatively, Armis is connected by road to the next entry Ardaoneon (R&C 43). 
    Alfoldean (TQ1133) on the River Arun, formerly Tarrant
    Hassocks (TQ2915) on Albourne?
Anstiebury (TQ1544) could suit our needs. The name Anstie and its variants are commonly recorded as Anesti(ge) OE ānstīge 'narrow or lonely track', or 'track linking other routes'. While a somewhat common name, this is on a Roman road next the significant place-name Coldharbour, with finds of a Roman building and Romano-British pottery. *Annis- + Br.*tego 'house'?

    Alfodean TQ 1133 on the River Arun, precedes Ardaoneon (R&C 43) Hardham on a path down Stane Street to Chichester. The River Arun was recorded as Trisantonis in Ptolemy's Geography, with later records substantiating the connection. But rivers can be known by different names; the lower course having one name, the upper course another. For example, the Somerset Earn is know as the Isle in its upper reaches, both undoubted British names. See also ERN pp xxxix-xl.
    Were *Arnus, root Arno- 'run, go', to be the name of the upper course; and Trisanto 'one who goes across, a trespasser'* that of the lower, there need not be any conflict. The lower reach, being prone to high tides and flooding would carry the name Trisanto. The upper reach is perhaps as simple as Mills' Earn 'flowing one', though Ekwall cites many possibilities. Arundel may be Arno-dale, rather than Dr. Bradley's longstanding 'horehound dale'.
    The density of names already matched to the significant sites in this region is rather high. Unmatched are Neatham and the much later Portchester.

*Ekwall ERN p.418