Desserobdella picta
| Desserobdella picta | |
|---|---|
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| An close-up image of Desserobdella picta | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Annelida |
| Clade: | Pleistoannelida |
| Clade: | Sedentaria |
| Class: | Clitellata |
| Subclass: | Hirudinea |
| Order: | Rhynchobdellida |
| Family: | Glossiphoniidae |
| Genus: | Desserobdella |
| Species: | D. picta |
| Binomial name | |
| Desserobdella picta (Verrill, 1872) | |
| Synonyms[1] | |
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Synonymy
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Desserobdella picta is a species of leech widespread across North America[1] in freshwater habitats. They are members of the phylum Annelida, or "segmented worms". Leeches are ectoparasites that can parasitize a wide range of vertebrates, with some species even specializing in specific hosts.
Desserobdella picta most commonly found feeds on the blood of amphibians like frogs and salamanders,[2] but have also been recorded feeding on turtles.[3] They can be commonly characterized by their distinct markings and the small papillae on their backs.
Description
Desserobdella picta is a small leech with a flattened oval to elongate body. A line of chromatophores runs down the middle of the body forming a line that can be distinct or indistinct. Their bodies are brownish-green with orange. They have two pairs of eyes grouped closely together, and a pair of salivary glands located at the base of its proboscis.[4]
Taxonomy
The species was first described as Clepsine picta by American zoologist Addison Emery Verrill in 1972.[4]
Their genus, Desserobdella, groups them with similar species, sharing distinct morphological and ecological traits.
Physiology
Desserobdella picta has a more dispersed gland arrangement than other leeches in the same genus with two mucous and two protein secretions, and its salivary cells consist of a spherical body and an elongated duct, with secretory granules densely packed inside, which are released through pores located at various points along the proboscis. This uniquely structured salivary gland system is a defining synapomorphy of the species, along with its two pairs of coalesced eyes, where the front pair is larger than the back pair.[5]
Additionally, D. picta possesses paired, sac-like structures—sometimes called "mycetomes"—that open into the esophagus midway between the base of the muscular proboscis and the first crop caeca, where blood is stored between feedings. This glandular structure is characteristic of all leeches in the Placobdella group.
Feeding
Leeches feed by attaching to their host and using specialized mouthparts to suck blood. In addition to their blood-feeding abilities, some leeches, such as Desserobdella picta, rely on bacterial symbionts housed within their mycetomes to aid in their nutrition. Recent research has shown that these leeches can sustain themselves through endosymbionts, a newly identified lineage of alphaproteobacteria related to the Rhizobiaceae, housed within their mycetomes. However, it remains unclear how these bacterial symbionts were acquired or their precise evolutionary relationships.[6] These symbiotic bacteria, found within specialized structures in the leech's body, are thought to help synthesize essential nutrients like B vitamins that are scarce in vertebrate blood. The bacteria associated with leeches are typically members of the Gammaproteobacteria class, and they are believed to be vertically transmitted from parent to offspring. This long-term symbiotic relationship enhances the leech's ability to feed and survive on a diet of blood, compensating for the nutritional limitations of their host's blood. The presence of these symbionts is a key factor in the survival and evolution of blood-feeding leeches, supporting their feeding strategy beyond the mere consumption of blood.[7]
Movement
They move using two primary methods: looping (inchworm-like movement) and swimming. When looping, they use their two suckers—the anterior sucker at the front and the posterior sucker at the rear—to anchor themselves to a surface. They attach the posterior sucker, stretch their body forward to secure the anterior sucker, then release the posterior sucker and pull it forward, creating a characteristic inchworm-like motion. In water, many leeches swim by undulating their bodies in a wave-like motion, contracting and expanding their muscles rhythmically to propel themselves forward. These adaptations allow leeches to navigate both terrestrial and aquatic environments efficiently.
Lifecycle
Leeches show diverse parental care behaviors, which influence what happens to their cocoons and offspring after they are laid. Most leeches secrete cocoons from the clitellum, slip them off their heads, and leave them behind in a protective casing that resists environmental changes, providing no further care. Piscicolid and erpobdelliform leeches attach hardened cocoons to smooth surfaces, while hirudiniform leeches leave the water to deposit their cocoons on moist shorelines before abandoning them. In contrast, glossiphoniid leeches produce fragile, membranous cocoons that they actively guard. These leeches stay with their cocoons until the embryos hatch, after which the hatchlings attach to the parent's underside. In blood-feeding species, the young remain there until the parent carries them to their first meal.[8]
This close association between parent and offspring begins even before hatching, as leeches reproduce through a process called hypodermic implantationhis close association between parent and offspring begins even before hatching, as leeches reproduce through a process called hypodermic implantation, in which the male injects sperm packets directly into the female's body, allowing fertilization to occur internally. This method of reproduction is common among certain leech species and ensures successful transfer of genetic material. After fertilization, the female lays her cocoons on a solid surface, such as submerged rocks or aquatic vegetation, rather than attaching them to a host. This strategy provides a stable environment for the developing embryos. Once the embryos hatch, they do not immediately disperse; instead, they move to the underside of the parent leech, where they remain attached for a period of time. This parental association may offer protection and increase their chances of survival in their early developmental stages before they become independent.[9]
Ecology
Desserobdella picta plays a crucial ecological role in freshwater ecosystems as both a parasite feeder and a vector for the blood parasite Trypanosoma fallisi, which infects the American toad (Bufo americanus). Within the leech, the parasite undergoes key developmental stages, first transforming in the crop before migrating to the proboscis, a process influenced by the digestion rate of the blood meal. While inside D. picta, trypanosomes exhibit various forms, some resembling those seen in laboratory cultures. Additionally, flagellates within the leech have been observed to contain intracellular microorganisms, suggesting interactions with other microbes that may influence nutrient cycling and parasite dynamics. The presence of D. picta in aquatic habitats also serves as an indicator of environmental conditions, reflecting the health of freshwater systems. Despite its ecological significance, challenges in classification and identification persist due to its morphological similarities with related species.[9]
References
- 1 2 "Desserobdella picta (Verrill, 1872)". www.gbif.org. Retrieved 2025-03-19.
- ↑ Hovingh, Peter; Linker, Alfred (November 1999). "Hyaluronidase activity in leeches (Hirudinea)". Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. 124 (3): 319–326. doi:10.1016/s0305-0491(99)00128-5. ISSN 1096-4959. PMID 10631807.
- ↑ Watermolen, Dreux J. (June 1996). "Notes on the Leech Desserobdella picta (Hirudinea: Glossiphoniidae)". Journal of Freshwater Ecology. 11 (2): 211–217. Bibcode:1996JFEco..11..211W. doi:10.1080/02705060.1996.9663480. ISSN 0270-5060.
- 1 2 Barta, John R.; Sawyer, Roy T. (1990-09-01). "Definition of a new genus of glossiphoniid leech and a redescription of the type species, Clepsine picta Verrill, 1872". Canadian Journal of Zoology. 68 (9): 1942–1950. Bibcode:1990CaJZ...68.1942B. doi:10.1139/z90-273. ISSN 0008-4301.
- ↑ Moser, William E.; Desser, Sherwin S. (July 1995). "Morphological, histochemical, and ultrastructural characterization of the salivary glands and proboscises of three species of glossiphoniid leeches (Hirudinea: Rhynchobdellida)". Journal of Morphology. 225 (1): 1–18. doi:10.1002/jmor.1052250102. ISSN 0362-2525. PMID 7650743.
- ↑ Siddall, Mark E; Perkins, Susan L; Desser, Sherwin S (January 2004). "Leech mycetome endosymbionts are a new lineage of alphaproteobacteria related to the Rhizobiaceae". Molecular Phylogenetics and Evolution. 30 (1): 178–186. Bibcode:2004MolPE..30..178S. doi:10.1016/S1055-7903(03)00184-2. PMID 15022768.
- ↑ Perkins, Susan L.; Budinoff, Rebecca B.; Siddall, Mark E. (September 2005). "New Gammaproteobacteria Associated with Blood-Feeding Leeches and a Broad Phylogenetic Analysis of Leech Endosymbionts". Applied and Environmental Microbiology. 71 (9): 5219–5224. Bibcode:2005ApEnM..71.5219P. doi:10.1128/aem.71.9.5219-5224.2005. ISSN 0099-2240. PMC 1214607. PMID 16151107.
- ↑ Borda, Elizabeth; Siddall, Mark E (January 2004). "Arhynchobdellida (Annelida: Oligochaeta: Hirudinida): phylogenetic relationships and evolution". Molecular Phylogenetics and Evolution. 30 (1): 213–225. Bibcode:2004MolPE..30..213B. doi:10.1016/j.ympev.2003.09.002. ISSN 1055-7903. PMID 15022771.
- 1 2 Light, Jessica E.; Siddall, Mark E. (October 1999). "Phylogeny of the Leech Family Glossiphoniidae Based on Mitochondrial Gene Sequences and Morphological Data". The Journal of Parasitology. 85 (5): 815–823. doi:10.2307/3285816. ISSN 0022-3395. JSTOR 3285816. PMID 10577715.