Molecular and morphological characterization of a haemogregarine in the alligator snapping turtle, Macrochelys temminckii (Testudines: Chelydridae)

摘要

A severely underweight alligator snapping turtle Macrochelys temminckii Troost in Harlan, 1835, was found near Tyler, Texas, and taken to the Caldwell Zoo. Blood films were submitted to Texas A&M University, College Station, Texas, for morphological and molecular identification of haemogregarine-like inclusions in the red blood cells. Intraerythrocytic Haemogregarina sp. forms were found on microscopic examination at a parasitemia of <1 %. The morphology and morphometric data for the forms indicate similarity to Haemogregarina macrochelysi n. sp. Telford et al., 2009, previously reported in alligator snapping turtles in Florida and Georgia, but two characteristic stage forms were not shared between H. macrochelysi n. sp. and the parasite found in this report. The haemogregarine 18S ribosomal RNA gene (1555-bp fragment) was amplified and cloned, and five clones sequenced. The sequences were deposited in the NCBI GenBank database. All five showed similar to 96 % identity to Haemogregarina balli Paterson and Desser, 1976, Hepatozoon sp., and Hemolivia stellata Petit et al., 1990. A 774-bp segment shared 98-99 % identity with the corresponding Haemogregarina sp. rDNA sequence (KR006985) from Caspian turtles (Mauremys caspica McDowell, 1964) in Iran. A neighbor-joining phylogenetic tree generated from aligned sequences from the clones, 26 hematozoa, Adelina dimidiata Schneider, 1875, and Cryptosporidium serpentis Levine, 1980, revealed the cloned sequences clustered on their own branch within the Haemogregarina spp. clade. No genetic data are available for H. macrochelysi n. sp. at this time, so it remains unclear if this parasite in a Texas alligator snapping turtle is conspecific with H. macrochelysi n. sp.