Chthamalus, Ranzani, 1817

Chan, Benny K. K., Tsai, Pei-Chen & Tsao, Yao-Feng, 2024, A new intertidal barnacle, Chthamalus ngankeeae sp. nov. (Balanomorpha: Chthamalidae) from the Malaysian Peninsula and western Borneo waters, Zootaxa 5476 (1), pp. 26-43 : 39-40

Species identification key for Chthamalus of the ‘ challengeri subgroup’ in the Indo-Pacific

1. Junction of external shell plates joined by interlocking teeth........................................... C. dentatus

– Junction of external shell plates not joined by interlocking teeth................................................ 2

2. Junction of the scutum and tergum sigmoid................................................................. 3

– Junction of the scutum and tergum not sigmoid but straight.................................................... 6

3. Cirri III antenniform......................................................................... C. antennatus

– Cirri III normal, non-antenniform........................................................................ 4

4. Four or five depressor muscle crests on tergum.............................................................. 5

– Two or three depressor muscle crests on tergum........................................................ C. dalli

5. Adductor muscle scar on scutum deep........................................................... C. challengeri

– Adductor muscle scar on scutum shallow........................................................... C. barnesi

6. Shell surface strongly ribbed............................................................................ 7

– Shell surface not strongly ribbed......................................................................... 8

7. Scutum without prominent articular ridge............................................................. C. moro

– Scutum with articular ridge............................................................ C. ngankeeae sp. nov.

8. Scutum equilateral triangular................................................................... C. williamsi

– Scutum depressed, width greater than height........................................................ C. sinensis