Roman Cavalry research and the modelling of 'mid' Imperial Roman Light Cavalry

[CarlL]

As I type my subject line I hear myself question its assumptions: "What is mid Imperial?" "Was there a light cavalryman or just cavalry that could be scouts and pursuers of the broken and battle line cavalry?" and "Carl its a long time since you did any serious reading of research on these topics."....
All sparked by a friend sharing an image of one of many 28mm MIR Light Horse models he is rightly proud to be adding to his Roman Forces to smite me on the tabletop some time soon!
My initial thought was isn't that an Arab "ters" style shield he is carrying? And were there any Arab units in Roman army? There was (I recall) a brief reigning Emperor known (in modern times or historically?) as "Philip the Arab".
Then I thought is that a representation of a linen tunic he is wearing or a leather 'mackintosh' or cowboy duster coat of linen or canvas? We know the Badawa (Bedouins) adopted long robes for protection from sun and sandstorms. But is this figure based on other non Arab ideas about a MIR cavalry trooper and his linen robes? I consulted my small library about Roman cavalry shields and dress but to no avail: it's all either early (ie Augustan) Empire material or "Late" Roman (post Hunnic) material.
So here I am seeking enlightenment in the home of 'Ancients' wargaming! HELP!!?? Hopefully attached is an image of the rider sparking my questions!
CarlL 

[Duncan Head]

My initial thought was isn't that an Arab "ters" style shield he is carrying?

It does look like a mediaeval Arab turs, yes. There are similar shields on Palmyran monuments - here for instance - which may be the inspiration, but I can't think of any that are strictly Roman, at the moment.

And were there any Arab units in Roman army?

-  Ala Parthorum et Araborum
-  The Nabataean standing army seems to have been incorporated, after the annexation of the kingdom, as auxiliary units named Petraea after the capital Petra - Cohors III Ulpia Petraeorum equitata for instance
- In the Late Empire, there are several Equites Saraceni in the Notitia.

The question of whether there were Middle Imperial "light cavalry" at all is uncertain. Phil Barker argued that the "Illyricani" units introduced in the mid-third century were unarmoured javelin-armed cavalry: he extended this to units entitled Delmatae or Dalmatae, Promoti, and Mauri. Others have suggested that these units were conventional mailed javelin-and-spear cavalry - perhaps except the Mauri, who may have maintained the old Moorish style of equipment and tactics. (There is a Michael Speidel article on the spread of Moorish equipment to Roman units, but that's specifically in North Africa.)

[CarlL]

Cheers Duncan.
CarlL