A phylogenetic assessment of the branchiobdellidan family Branchiobdellidae (Annelida, Clitellata) using spermatological and somatic characters

Abstract

The spermatozoa of six species belonging to the branchiobdellidan family Branchiobdellidae (i.e. Xironogiton victoriensis, Cirrodrilus kawamurai, Ankyrodrilus legaeus, Xironodrilus formosus, Branchiobdella kobayashii, Branchiobdella orientalis) were studied and compared to the other sperma-tozoa already described in the group. A parsimony analysis was performed on the spermatozoal data of the species examined, as well as on their somatic characters. The results of the two analyses were contrasted and a further parsimony analysis was run on the matrix comprising both sets of characters. The study of sperm ultrastructure confirmed the genera recognized with traditional somatic characters and the monophyly of the branchiobdellidans. Xironodrilus was proved to be the sister species of Ankyrodrilus and its inclusion into the family Branchiobdellidae was supported. Evolutionary hypotheses on intergeneric differences in the family consistent with its biogeography can be suggested by the cladograms: Xironogiton is an early offshoot of branchiobdellidan lineage migrating to North America and probably radiating only in recent times; Branchiobdella kobayashii has a spermatozoon completely different from that of the other species of the genus, thus suggesting a complex story for this widespread taxon with a disjunct distribution

Phylogeny of oligochaetous Clitellata

“…First, a particular focus on spermatozoal ultrastructure and 'spermiocladistics' (Jamieson, 1987a) during the last 20 years has proved beneficial for inferring clitellate relationships. Clitellate spermatozoa show several synapomorphic features (see, e.g., Jamieson, 1986;Ferraguti, 2000), but also a great variation that has been explored in numerous papers (e.g., Garavaglia et al, 1974;Jamieson, 1978Jamieson, , 1982Jamieson, , 1983Jamieson, , 1984Jamieson, , 1987aJamieson, , 1987bBraidotti & Ferraguti, 1982;Jamieson et al, 1983Jamieson et al, , 1987Ferraguti, 1984Ferraguti, , 2000Ferraguti et al, 1989Ferraguti et al, , 1994Ferraguti & Gelder, 1991;Westheide et al, 1991;Erse´us & Ferraguti, 1995;Westheide & Purschke, 1996;Cardini et al, 2000;Gelder & Ferraguti, 2001;Marotta et al, 2003). These studies demonstrate that sperm often carry a phylogenetic signal that is congruent with that of other morphological data.…”

Diversity of spermatozoan morphology in two families of Branchiobdellida (Annelida: Clitellata) from North America

“…The space is always filled with moderately electrondense subacrosomal material and in a few species it may contain an electron-dense acrosome rod. The rods show varying degrees of stainability and sometimes are only slightly more electron-dense than the surrounding material, as described in Xironodrilus formosus (Cardini et al 2000). An acrosome rod is, however, always clearly present in the early stages of spermiogenesis (M. Ferraguti, unpublished observations) and it is assumed that the structure remains in the mature spermatozoon, even though the reason for the variation in stainability of the rod is unclear.…”

“…Having demonstrated a surprising level of diversity in branchiobdellidan spermatozoon morphology and supported the statement with detailed results from the Branchiobdellidae + Xironodrilidae (Cardini et al 2000), the remaining major branchiobdellidan families needed to be examined in detail to see if any further character state existed. Therefore, the present investigation was designed to describe spermatozoa from representative species in the Bdellodrilidae and Cambarincolidae that would reveal the diversity of characters from an intergeneric aspect and from an interspecific aspect in the largest branchiobdellidan genus, Cambarincola.…”

“…The spermatozoa of Branchiobdella species proved to be quite atypical of those of the branchiobdellidans, thus not supporting Sawyer's hypothesis. Given the morphological diversity reported by Ferraguti and Gelder (1991), six species from the Branchiobdellidae + Xironodrilidae representing each of the three distributional regions were studied to determine if zoogeography could account for the degree of spermatozoan variation in this group (Cardini et al 2000). The study confirmed the large variability of sperm morphology in the group and dispelled any idea that a single "branchiobdellidan spermatozoon model" exists or that there are any zoogeography-based ultrastructural characters.…”

Biological and morphological aspects ofBranchiobdella italica(Annelida: Clitellata) in a native crayfish population of central Italy

“…The systematics and ranking of this group remained a matter of debate for a long time (Holt 1986;Gelder & Brinkhurst 1990;Cardini et al 2000). However, recent molecular studies (Martin 2001;Siddall et al 2001;Erséus & Källersjö 2004) recognized branchiobdellidans as a monophyletic taxon, sister-group to Lumbriculida (McHugh 2000) within Clitellata (Gelder & Brinkhurst 1990;Gelder 1996;Gelder & Siddal 2001;Siddall et al 2001).…”