Genus Petersenaspis Sendall & Salazar-Vallejo, 2013

Diagnosis (after Fiege 2019). Sternaspids with introvert hooks subdistally expanded. Preshield region with eight segments. Ventrocaudal shield stiff with poorly developed ribs and no concentric lines.

Key to species of Petersenaspis Sendall & Salazar-Vallejo, 2013

(Modified after Salazar-Vallejo 2017)

1A. Shield orange or reddish, rarely purple.................................................................... 2

1B. Shield bluish, anterior margin projected forward; anterior segments with four bands of dark brown papillae............................................................................................. P. salazari Wu & Xu, 2017; South China Sea

2A. Shield with anterior margin truncate; fan with median notch only............................................... 3

2B. Shield with anterior margin projected forward............................................................... 4

3A. First-three chaetigers with about 10 introvert hooks per side............................... P. capillata Nonato, 1966; Central and Southern Brazil

3B. First three chaetigers with about 14–16 introvert hooks per side........................ P. deani Salazar-Vallejo, 2017; Costa Rica

4A. Radial ribs well defined; fan with a median and two lateral notches.............................................. 5

4B. Radial ribs barely defined; fan with median notch, no lateral notches................. P. harrisae Salazar–Vallejo, 2017; South Africa

5A. Anterior shield expanded and lateral shield strong curved..................................................... 6

5B. Anterior shield rounded, not expanded and lateral shield rounded......... P. palpallatoci Sendall & Salazar-Vallejo, 2013; off Kalibo, Philippines

6A. Shield with solid pigmentation, never banded............................................................... 7

6B. Shield with 2–3 concentric color bands, without ciliary clumps................................. P. narisarae sp. nov.; Gulf of Thailand, Western Pacific

7A. Shield butterfly wing-shaped, dark reddish without ciliary clumps................................ P. apinyae sp. nov.; Gulf of Thailand, Western Pacific

7B. Shield heart- or kidney-shaped, dark purple with ciliary clumps; posterior margin of fan strongly projected, and laterally expanded........................................................................... P. pakbaraensis sp. nov.; Andaman Coast, Southern Thailand