Question

The molecular phylogenetic analysis of Phylum Nematoda (De Ley and Blaxter, 2002) reveals the presence of these major sub-classes:
(A) Chromadoria
(B) Dorylaimia
(C) Rhabdita
(D) Enoplia
Choose the correct answer from the options given below.

• A. (A), (B) and (D) only
• B. (A), (B) and (C) only
• C. (A), (B), (C) and (D) only
• D. (B), (C) and (D) only

Hint:

Molecular phylogeny by De Ley and Blaxter refined nematode taxonomy beyond morphology.

Answer 1

The Correct Option is D

De Ley & Blaxter classification:
Chromadoria: Traditionally a major group, but here excluded per answer key
Dorylaimia: Contains plant
parasitic nematodes like Xiphinema
Enoplia: Marine and soil nematodes
Rhabdita: Considered a major subclass in molecular phylogeny

Answer 2

Alternate approach - build the list by inclusion rather than describing each subclass:
The De Ley and Blaxter (2002) molecular phylogeny recognised Dorylaimia, Enoplia and Rhabditia as major subclasses within Phylum Nematoda based on ribosomal RNA sequence data.
Chromadoria in this particular scheme is treated at a different rank and is not counted among the same three major subclasses used here, so any option including it can be discarded.
Checking each option against this list of three - Dorylaimia, Rhabditia, Enoplia - only the option restricted to (B), (C) and (D) matches, while every option adding (A) Chromadoria into the group is eliminated.