---
title: Red Dwarf Flatworm (Pseudoceros rubronanus)
scientific_name: Pseudoceros rubronanus
common_name: Red Dwarf Flatworm
taxon: Flatworms
published: 2026-08-10T21:29:09.410Z
updated: 2026-08-11T06:31:58.742Z
tags: Red Dwarf Flatworm, Pseudoceros rubronanus, Flatworms, Red Sea, Marine Life, Diving
url: https://redseacreatures.com/taxon/invertebrate/worms/flatworms/red-dwarf-flatworm
---

# Red Dwarf Flatworm (*Pseudoceros rubronanus*)

## Quick facts

- **Group:** Flatworms (*Pseudocerotidae*)
- **Size:** up to 2 cm
- **Depth:** 2-25 m
- **Diet:** Carnivore
- **Activity:** Nocturnal
- **Rarity:** Rare
- **Habitat:** Rubble and coral heads, often in crevices
- **Reproduction:** Egg layer, Simultaneous hermaphrodite
- **Hazard:** Poisonous

## How to recognise it

- pink to red body with clusters of small white dots
- bright fuchsia margin
- tiny, about 2 cm
- usually deep in rubble rather than out in the open

Pink through red, clustered with small white dots and edged in bright fuchsia, and no more than 2 cm (0.8 in) long. Size is what makes it rare rather than scarcity: an animal this small in rubble is found by people who are already looking at rubble, which is a smaller group than it should be.

Like its relatives it feeds on sessile prey, glides on cilia over a slick of its own mucus, and carries toxins in the skin that make the color worth advertising. What it does not have is a way to fight, run or hide, so the entire defense is the honesty of that signal.

The name is straightforwardly descriptive - red, and a dwarf even among flatworms - and dates from 1998. Much of this genus was described in the 1990s by Newman and Cannon working through the Indo-Pacific, which is why so many local species carry authorship younger than the divers photographing them.

## Also known as

- **French:** Ver plat rouge
- **Russian:** Плоский червь красный карликовый

## Range

Australia, Papua New Guinea

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*Source: [Red Sea Creatures](https://redseacreatures.com/taxon/invertebrate/worms/flatworms/red-dwarf-flatworm)*
*Updated: August 11, 2026*