I have found the following OOB for the Italians at Derna/Mechilli:
Fteiah airfield area (east of Derna): 4 M11/39 tanks, 6-20mm guns, 60th Bersaglieri Motorcycle Company (less 2 platoons).
Fort Rudero, Fteiah plain: 2 x 75/27 guns 1 x 47/32 gun, and a machinegun platoon
Martuba-Derna crossroad: Tonini battalion: a 75/27 field arty battery from 10th Arty Rgt, eleven 47/32 AT guns, six 20mm guns.
Wadi Derna (southern portion of the Derna line): 2nd Battalion, 86th Inf. Rgt., Sabratha Division, Depot infantry battalion from 115th Inf. Rgt, Marmarica Division, 17th Machinegun Battalion from Brescia Division.
Town of Derna: Elements, 55th Machinegun Bn from Savona Division 18th Libyan Inf. Bn. an artillery battery.
Fort Piemonte, Fteiah plain: 2 x 75/27 guns 1 x 47/32 gun, a machinegun platoon
Reserve: 2 platoons of 201st Bersaglieri Motorcycle Coy. 4 x 20mm guns 2 armored cars (decrepit Lancia WWI model) a Motorcycle Carabinieri team.
Derna Sector Artillery: 1st Group (Battalion), 75/27 field guns (20 guns used in anti-tank role) 7th Group, 75/46 AA guns (7 guns), 5th 20mm AA battery, 256th 65/17 light gun battery, 5 x 47/32 guns, one 76/40 gun battery, two 102/45 gun batteries, one 152/45 gun battery, one 120/45 gun battery, seven Scotti light guns.
Mechilli sector: Bambini Armored brigade (2 medium tank battalions, 1 motorcycle battalion, artillery and support units) with 10th Bersaglieri Regiment (2 battalions) and another medium tank battalion on the way.
The Libyan parachutists (480 men) were combined with the Pancano Group (370 men, 3-47/32mm guns, 4-75/27 guns, 12-20mm guns, 4 M11/39 tanks, 1 captured Humber armored car, 22 trucks and 12 motorcycles.) to form the Tonini Battalion (850 men, 8x 47/32mm guns, 8 Fiat M35 machineguns, 30 Breda M30 LMGs, 12x 20mm guns, and 5 batteries of 75/27mm guns.).
The XX HQ flag on our posted map by Maurizio includes the 85th Regiment of the 60th Division.
On January 23rd the immediate area around Derna under General Bergonzoli numbered approximately 5,000 men and a fair amount of heavy, field and light artillery units. The whole sector from Derna down to Mechilli then up to Barce and Giovanni Berta totaled some 11,000 men.
Source: Italians vs Australians in Derna, 1940 by Stefan Farrelly, Line of Comunications, December 2007 pages 28-29
Does any of this agree?
The Australians are given as 2/4, 2/5, 2/6, 2/7, 2/8 battalions of the 19th brigade.