Putting in shape – towards a unified approach for the taxonomic description of monogenean haptoral hard parts

Abstract

Among monogeneans, haptoral hard parts provide prominent morphological characters upon which identifications are largely based. Traditionally, morphometric approaches are based on the use of arbitrary collections of linear distance measurements between landmarks. An exhaustive review of the specific diagnoses published in the journal Systematic Parasitology highlights the fact that an intricately important number of measurements are used to describe the same morphological features. Hence, this does not allow relevant comparison between studies and may have caused confusion in the literature. More importantly, a significant proportion of diagnoses commonly used do not maximize the amount of information available from morphological features, and sets of linear measurements between landmarks do not properly allow the complete reconstruction of the shape of haptoral hard parts. Given this prominent bias and the disparate use of traditional methodologies, I suggest the use of alternative methods in systematic parasitology that fully take into consideration the shape of morphological features. In addition to these considerations, a move toward placing shape at the centre of automated species recognition would be mutually beneficial for both taxonomists and non-taxonomists.

Co-Speciation of the Ectoparasite Gyrodactylus teuchis (Monogenea, Platyhelminthes) and Its Salmonid Hosts

“…Morphological species identification is usually based on only a few characters and is far from straightforward as it requires sophisticated morphometric techniques [57]. Molecular species identification in Gyrodactylus was therefore highly welcomed, and currently relies largely on sequencing of the ribosomal internal transcribed spacers (ITS).…”

Constraining the Deep Origin of Parasitic Flatworms and Host-Interactions with Fossil Evidence

“…Considering that multiple authors (Upeniece, 2001(Upeniece, , 2011Littlewood and Donovan, 2003) have suggested that the Middle Devonian hook circlets might belong to a platyzoan helminth, a putative reinvestigation of these fossils could be used to constrain the evolutionary history of this entire group. Many studies on extant flatworms have focused on the hook elements of particular groups (Vignon and Sasal, 2010;Vignon, 2011) or taxa (Shinn et al, 2003). Information and illustrations of these helminth structures can also be found in comprehensive systematic treatments: Yamaguti (1959), Schmidt (1986) and Khalil et al (1994) for Cestoda; Yamaguti (1963a) for Monogenea and Yamaguti (1963b) and Golvan (1969) for Acanthocephala.…”

Automated identification of Monogeneans using digital image processing and K-nearest neighbour approaches

“…In particular, the haptoral attachment organ is characterized by sclerotized structures such as anchors, bars, hooks, etc. The morphology of these organs are usually unique to monogenean species [5] and are used as diagnostic characters in taxonomy [6, 7]. …”