Tylenchulus semipenetrans is a –

✅Explanation:
Tylenchulus semipenetrans, also known as the citrus nematode, is a semiendoparasitic nematode. This means that the anterior part of the female nematode (head and neck) penetrates and establishes itself inside the root cortex, while the posterior part remains outside the root. This unique feeding behavior allows the nematode to derive nutrients from the plant while still maintaining contact with the external environment.
[Image of Tylenchulus semipenetrans (citrus nematode)]

📌Other Options Explanations:
(a) Ectoparasitic: Ectoparasitic nematodes feed on the external surfaces of plants, such as roots, without penetrating the plant tissues.
(b) Endoparasitic: Endoparasitic nematodes live and feed completely within plant tissues.
(d) Parasite of above ground part: Tylenchulus semipenetrans specifically infects the roots of citrus and other host plants. It does not parasitize above-ground plant parts.