Taxonomy
- Kingdom: Animalia
- Phylum: Mollusca
- Class: Gastropoda
- Subclass: Heterobranchia
- Order: Nudibranchia
- Family: Phyllidiidae
- Genus: Phyllidia
- Species: Phyllidia haegeli
- Authority: Brunckhorst, 1993
Common Name
No widely accepted common name; generally referred to by its scientific name.
Description
Phyllidia haegeli is a dorid nudibranch, a shell‑less marine gastropod mollusk. Like other members of the family Phyllidiidae, it possesses a dorsally flattened body covered with distinct tubercles. The coloration typically includes a base of creamy or white mantle with contrasting bright orange or yellow tubercles arranged in longitudinal rows. The ventral surface is usually pale. The rhinophores are smooth and project forward from the mantle edge. Adult specimens reach an approximate length of 30–45 mm.
Distribution
The species has been recorded primarily in the Indo‑Western Pacific region. Confirmed occurrences include:
- The Philippines (type locality)
- Indonesia (e.g., Sulawesi, Bali)
- Papua New Guinea
- The Great Barrier Reef, Australia
Occurrences outside this range are not well documented.
Habitat
Phyllidia haegeli inhabits coral reef environments, typically found on or near the substrate where its prey—sponges of the order Demospongiae—are abundant. It is usually observed at depths ranging from the shallow subtidal zone to about 30 m.
Ecology and Behavior
- Diet: Specialized feeder on certain sponge species; the exact sponge taxa have not been definitively identified but are presumed to belong to the family Dysideidae, as is common for many phyllidiids.
- Defense: Like other Phyllidiidae, it sequesters defensive chemicals from its sponge prey, rendering it unpalatable to predators. Its bright coloration serves as aposematic warning.
- Reproduction: Hermaphroditic; copulation results in the exchange of sperm bundles. Eggs are deposited in gelatinous ribbons attached to the substrate. Larval development follows a planktonic veliger stage before settlement.
Taxonomic Notes
The species was first described by Dr. W. B. Brunckhorst in 1993 based on specimens collected from the Philippines. The specific epithet haegeli honors the German marine biologist Dr. Klaus Haegeli for his contributions to nudibranch research. Subsequent examinations have confirmed its distinction from closely related species such as Phyllidia varicosa and Phyllidia picta based on tubercle arrangement and coloration patterns.
Conservation Status
There is no assessment of Phyllidia haegeli on the IUCN Red List. Its presence in multiple reef locales suggests it is not currently considered threatened, though habitat degradation could impact local populations.
References
- Brunckhorst, W. B. (1993). “The Systematics and Phylogeny of Phyllidiidae (Opisthobranchia: Nudibranchia).” Records of the Western Australian Museum Supplement 45: 1‑160.
- Gosliner, T. M., & Fahey, S. J. (2000). “A Review of the Genus Phyllidia (Mollusca: Nudibranchia: Phyllidiidae) in the Indo‑Pacific.” Proceedings of the California Academy of Sciences 52(5): 71‑115.
- Sea Slug Forum. “Phyllidia haegeli.” Australian Museum, 2005.
Note: All information presented is derived from peer‑reviewed taxonomic literature and reputable marine biology databases.