The Annelid Fauna of the Pacaya Samiria Reserve

1 Daniel H. Shain, 2 Maria I.A. Guavara

1 Biology Department, Rutgers The State University of New Jersey , Camden , NJ 08102 . 2 Universidad Nacional de la Amazonia Peruana, Iquitos, Peru.

List of taxa (7 spp.):

Class HIRUDINEA Lamarck, 1818

Order RHYNCHOBDELLIDA Blanchard, 1894

Family Glossiphoniidae Vaillant, 1890

Genus Helobdella Blanchard, 1896

Helobdella triserialis Blanchard, 1849

Fig. 1.

Helobdella sp. 1

Fig. 2.

Genus Haementaria Filippi, 1849

Haementaria sp. 1

Fig. 3.

Haementaria sp. 2

Fig. 4.

Family Ozobranchidae P into, 1921

Genus Ozobranchus De Quatrefages, 1852

Ozobranchus sp.

Order ARHYNCHOBDELLIDA Blanchard, 1894

Family Semiscolecinae Scriban and Autrum, 1934

Genus Semiscolex Kinberg, 1866

Semiscolex similis Weyenbergh, 1879

Class OLIGOCHAETA Huxley, 1875

Order HAPLOTAXIDA

Family Naididae

Genus Allonais Sperber, 1948

Allonais sp. 1 (probably inaequalis Stephenson, 1911)

Fig. 5.

Photographs:

Fig. 1. Helobdella triserialis variants. Two eyes, parallel longitudinal stripes along dorsum, suckers continuous with body, adults 1 - 1.5 cm extended, predaceous to molluscs. At least 4 variants with respect to dorsal pigmentation: A) 5 longitudinal rows of pigmented tubercles; B) 3 longitudinal rows; C) single row along dorsal midline; D) dorsal tubercles absent.

Fig. 2. Helobdella sp. 1 variants . Two eyes, dorsal pigmentation arranged in lateral rows (A) or randomly distributed (B), suckers continuous with body, adults up to 1 cm extended, probably predaceous to molluscs.

Fig. 3. Haementeria sp. 1. Most with two eyes (at least one specimen with four), anterior and posterior suckers distinct, peripheral markings, semi-transparent without blood, extensive diverticula, embryos carried on venter, adults up to 4 cm extended, good swimmer, probably parasitic to fish and amphibians (several picked from human swimmers).

Fig. 4. Haementeria sp. 2. Eyes not apparent on adult specimens, heavily pigmented, numerous tubercles on dorsum, adults up to 6 cm extended, good swimmer, probably parasitic to reptiles (several picked off human swimmers).

Fig. 5. Allonais sp. 1 (A) Adult worms up to 1 cm, 250 m m diameter; (B) ventral setae sigmoidal bifid in clusters of 3-5, dorsal rows with one hair and one palmate setae per cluster (C). Scale bars = 20 m m. 

Abstract of research findings: 

As part of a multidisciplinary effort aimed at identifying aquatic animal fauna in the Peruvian Amazon, a region within the Pacaya-Samiria National Reserve ( Loreto , Peru ) was sampled for annelids during September, 2002. Among the 447 specimens collected, at least seven different species are represented, six of which are hirudinid (leech) species. These include predaceous and blood-sucking glossiphoniids (e.g., Helobdella, Haementeria sp., respectively), one Hirudidae ( Orchibdella ) and a new member of the family Ozobranchidae. Surprisingly, only one oligochaete species (Naididae) was collected. With few exceptions, annelid specimens were found along the periphery of floating vegetation, just below the waterline. 

Phylogeny and Biogeography:

There are at least 13 annelid neotropical freshwater clades, including 8 oligochaetes, and 5 hirundinids. The oligochaete fauna is very poorly understood at the species level; the tubificid Allonais is known from the Neotropics and Africa . Hirundinids (leeches) are known from only six species in five families, suggesting this fauna is also poorly known at the species level. Haementeria species are unique to South America and have filled the niche occupied by Hirudo in Europe (i.e., mammalian bloodsuckers). The African counterpart, Placobdelloides jaegerskioeldi , probably diverged from the Haementeria lineage when the two continents separated. Helobdella species are the most widely distributed leeches worldwide. There has been some exchange between North and South American species, and probably not with Africa . Semiscolex has relatives on other continents; all are bloodsuckers with jaws. The South American species has lost its teeth but remains predaceous (e.g., on insect eggs, larvae). The African Semiscoloides is convergently similar. Ozobranchus is known from few species worldwide. The most notable, Ozobranchus margoi , is marine. Freshwater species are represented in Australia and Africa , where they are rare. Invasion from the sea is possible, but divergence from an ancestral stock seems more likely. In general, long-range dispersal of leeches is limited (although some can travel with their host, e.g., birds, turtles, fish). Some exchange occurs between continents, but the Peruvian specimens in question most likely diverged from common ancestors in South America and Africa .