Velvetworms of southern Africa's Journal

your questions here.

From ordinary photographs it appears that it is easiest to just use distribution for ID.
We really do need photographic features that are useful.
Summary to Date (June 2020)

Opisthopatus

Opisthopatus cinctipes Common Velvetworm - widespread

Opisthopatus amaxhosa Xhosa Velvetworm
Opisthopatus baziya
Opisthopatus camdebooi Camdeboo Velvetworm
Opisthopatus drakensbergi High Drakensberg Velvetworm
Opisthopatus highveldi Highveld Velvetworm
Opisthopatus kwazululandi Coastal Velvetworm
Opisthopatus roseus Pink Velvetworm
Opisthopatus swatii Swati Velvetworm

Peripatopsis

Peripatopsis balfouri Southern Blue Velvetworm - Widespread (Cape Peninsula to Hott Holl)
Peripatopsis lawrencei Ruens Velvetworm - Widespread (Peninsula to Riviersondernd & Ruens)

Peripatopsis alba Cave Velvetworm - Cape Peninsula
Peripatopsis capensis Peninsula Velvetworm - Cape Peninsula
Peripatopsis leonina Lions Head Velvetworm - Lions Head (CR - presumed extinct)
Peripatopsis stelliporata Table Mountain Velvetworm - Cape Peninsula

Peripatopsis cederbergiensis Cedarberg Velvetworm - Cedarberg

Peripatopsis sp1 - Groot Winterhoek
Peripatopsis purpureus Hawequas Velvetworm - Hex to Hawekwas to Hott Holl
Peripatopsis bolandi Boland Velvetworm - Hott Holl

Peripatopsis overbergiensis Overberg Velvetworm - Langeberg & Potberg
Peripatopsis clavigera Knysna Velvetworm - Garden Route - George to Plett
Peripatopsis sedgwicki Tsitsikamma Velvetworm - Knysna to PE

Peripatopsis hamerae Kamala Velvetworm - Eastern Cape
Peripatopsis storchi Katberg Velvetworm - Eastern Cape
Peripatopsis janni Amathole Velvetworm - Eastern Cape
Peripatopsis moseleyi Eastern Velvetworm - widespread: Eastern Cape

Peripatopsis birgeri Curry Velvetworm - KZN

Sources:
https://scholar.sun.ac.za/bitstream/handle/10019.1/100044/mcdonald_species_2016.pdf?sequence=1&isAllowed=y