Haminoea fusari

Turani, Martina, Valdés, Ángel & Malaquias, Manuel António E., 2024, Molecular phylogeny of the marine snail genus Haminoea (Gastropoda, Cephalaspidea): A framework to study marine diversity and speciation, Zoologica Scripta 53 (1), pp. 52-77 : 71

fusari complex

Another difficult case consists of groups 4, 5 and 6 in our phylogeny (Figure 1), which were rendered a single candidate species by the ABGD and ASAP molecular species delimitation methods. These three clades received maximum or nearly maximum support in both BI and ML analyses, but interestingly if considered together as a single clade the support lowers to 0.84 (PP) and 59% (BS), although this seems to be mostly influenced by the 16S gene data (Appendix S5). On the contrary, the haplotype network analysis (Figure 2) recovered the three groups as distinct, separated by 28 substitutions (between groups 4 and 6) and 21 substitutions (between groups 5 and 6) and showed a lack of shared haplotypes. Genetic distances were moderately high, ranging between 5.1% (between groups 5 and 6), 6.2% (between groups 4 and 6) and 7.4% (between groups 4 and 5).

This larger clade, including the three groups (4 + 5 +6), contains only specimens from the Mediterranean Sea and one from the Eastern Atlantic island of Selvagem Grande (Madeira Archipelago). They are all characterized by a distinct anatomical feature among Haminoea , namely a prostate with a constricted zone between the proximal and distal lobes (see Thompson, 1988). This feature has been described for the type species of the genus H. hydatis ( Talavera et al., 1987; Tchang, 1931; Thompson, 1976, 1981, 1988) and H. fusari ( Álvarez et al., 1993) . According to the literature these two species are basically distinguished by the presence of denticulated inner lateral teeth in H. hydatis ( Talavera et al., 1987; Tchang, 1931; Vayssière, 1885) while they are smooth in H. fusari ( Álvarez et al., 1993) .

Haminoea hydatis is the type species of the genus described by Linnaeus (1758) based on shells from the Mediterranean Sea. The type specimen illustrated in the webpage of the Linnean Collections, London (https:// linnean-online.org/16897/#?s=0&cv=0&z=0.0365%2C-0.0109%2C1.232%2C1.503), is a shell about 9 mm in height with a smooth surface. Vayssière (1885) studied specimens from the Gulf of Marseille on the Mediterranean French coast with smooth shells and a radula with inner lateral teeth denticulated, which he identified as H. hydatis . Later, Tchang (1931) described the male reproductive system of specimens from the same region as having a prostate with the proximal and distal lobes separated by a narrow tubular region, and Talavera et al. (1987) mentioned a smooth, cylindrical pointed penis. Thus, progressively it became established in the scientific literature the idea that H. hydays (originally only known from shells) was characterized by having smooth shells, radulae with denticulated inner lateral teeth and a prostate with a narrow region separating the two lobes. This view was reinforced by the fact that up until the end of the first half of the 20th century, the European fauna of Haminoea was basically restricted to two accepted species; either H. hydatis with its small smooth shells or H. navicula with larger and deeply spiralled shells.

However, several species with smooth shells accepted as valid (see Introduction) were described during the second half of the last century, one of them ( H. fusari ) also with a prostate with two lobes separated by a narrow region, but with smooth radular inner lateral teeth ( Álvarez et al., 1993). But the study of the holotype of H. fusari (MNCN 15.05/5356) revealed in fact the presence of mostly smooth inner lateral teeth, but interestingly some of them had the lower half denticulated. Intraspecific radular variability was described by Malaquias and Cervera (2006) for H. navicula and might occur also in specimens identified as H. fusari . This would basically make the two species anatomically undistinguishable and thus likely conspecific, rendering the name H. fusari a junior synonym of H. hydatis . In addition, the colour patterns of specimens in groups 4 and 5 are alike (data not available for group 3), with large unpigmented peri-ocular areas, dark upper sides of the parapodial lobes and fine bright-white dots along the edge of the cephalic shield, which further supports their conspecificity (see Figure 1).