Description of two novel Echinochasmus species (Digenea: Echinostomatidae) from the squacco heron Ardeola ralloides (Aves: Ardeidae) in Egypt: A light and scanning electron microscopic study

Abstract

Adult forms of two new echinostomatids were recovered from small intestine of six out of ten squacco herons, Ardeola ralloides collected from March to July 2019 from Giza governorate, Egypt. These small-sized parasites had a single row of collar spines with middle dorsal interruption, vitellaria reaching the level of ventral sucker and attributed to genus Echinochasmus, namely, E. ralloides n. sp. (prevalence 40%) and E. rawashi n. sp. (prevalence 20%). The morphometric features and differential indices of two species were measured, compared and described using light and scanning electron microscopy (SEM). The body of E. ralloides n. sp. measured 959.2-1090.6 × 264.3-311.1 μm (L × MW). It was provided with 26 collar spines (9 dorsal, 2 lateral and 2 angle on each side of the dorsal collar interruption), lacked of tegumental spines except for small areas in lower left and lateral right margins of ventral sucker, and characterized by presence of many minute pores of 3.1-3.8 μm on dorsal surface of hindbody. The body of E. rawashi n. sp. measured 638.8-1173.5 × 138.8-207.7 μm (L × MW), provided with 24 collar spines (7 dorsal, 2 lateral and 2 angle on each side of the dorsal collar interruption) and had scale-like tegumental spines distributed on whole ventral surface and anterior 1/4 of dorsal surface of body, ended by up to 13 digit-like structures and measured 2.1-2.5 × 4.4-4.8 μm.