Virilia, , Roberts, 1967

Zanata, Angela M. & Vari, Richard P., 2005, The family Alestidae (Ostariophysi, Characiformes): a phylogenetic analysis of a trans-Atlantic clade, Zoological Journal of the Linnean Society 145 (1), pp. 1-144 : 108-109

AND VIRILIA )

The remaining components of clade 23 include species currently assigned to the genera Hemmigrammopetersius , Rhabdalestes and Virilia . Difficulties in defining and distinguishing these genera led some authors to propose the synonymy of these taxa in various combinations ( Paugy, 1990a: 80; Géry, 1995: 46). Our phylogenetic results highlight some of the problems with the continued recognition of these taxa as now defined.

According to our analysis, the recognition of Hemmigrammopetersius and Virilia renders Rhabdalestes as an unnatural group. Despite the tree topology of these groups that indicates that the species of Rhabdalestes and Virilia included in this analysis should be synonymized in Hemmigrammopetersius , the first described of the three genera, such an action is clearly premature.

Possible changes in generic-level nomenclature within the clade would only be appropriately undertaken following a comprehensive phylogenetic study of Hemmigrammopetersius , Micralestes , Rhabdalestes and Virilia , including the type-species of Hemmigrammopetersius and Rhabdalestes , neither of which were available for inclusion in this analysis. Hemmigrammopetersius , Rhabdalestes and Virilia are consequently conserved as presently defined for the purpose of the following discussion. The clade composed of the examined species of Hemmigrammopetersius , Rhabdalestes and Virilia ( Fig. 43 , clade 26) is supported by the following seven synapomorphies:

173. Relatively large inner row tooth proximate to dentary symphysis absent (char. 88, 1> 0). Reversed in Virilia and occurs independently in Micralestes occidentalis , clade 39, clade 35 and in the basal genera Arnoldichthys , Hydrocynus and Petersius .

174. Distinct posterior curvature of third unbranched anal-fin ray and basal portions of immediately following rays present (char. 182, 0> 1).

175. Distinct anteroposterior thickening of third unbranched anal-fin ray present and moderately to well-developed (char. 183, 0> 1). Further modified in Virilia (see autapomorphy X 4 under that genus).

176. Basal portions of anterior branched anal-fin rays in males with posterior medial expansion overlapped laterally by anterior section of following rays (char. 184, 0> 1).

177. Attachment of ligaments of erector muscles on anterior branched anal-fin rays of males on anterolateral surface of somewhat more distal portion of ray (char. 186, 0> 1).

178. Posterodorsal extension of basal portions of anterior and middle branched anal-fin rays present (char. 190, 0> 1).

One ambiguous synapomorphy has been identified for this clade:

179. Connection between sensory canal in sixth infraorbital and laterosensory canals on neurocranium through pore located on pterotic or between junction of pterotic and frontal (char. 154, 1> 0). Either derived at this level or the opposite condition (state 1) was independently acquired in the clade consisting of Micralestes acutidens and M. occidentalis , in M. lualabae , Micralestes sp. , Alestes and Hydrocynus forskahlii .

MONOPHYLY OF CLADE 27

Within clade 26, Rhabdalestes eburneensis , for which no autapomorphies have been identified, is hypothesized to be the sister species to the clade consisting of Hemmigrammopetersius , R. septentrionalis , R. loenbergi , R. rhodesiensis and Virilia . This group, identified herein as clade 27, is supported by the following two synapomorphies:

180. Separation of inner and outer tooth rows on premaxilla less distinct than in most other alestids, with gaps present between first and second and second and third teeth of inner row and with two teeth of outer row partially repositioned into resultant gaps in inner tooth row (char. 58, 0> 1). Also independently acquired in clade 35.

181. Anterodorsal portion of ascending process of maxilla terminating in relatively pointed process (char. 67, 1> 0). Reversal of synapomorphy 43 at level of clade 6; also present independently in clade 31.

Rhabdalestes septentrionalis , the sister group to the clade consisting of Hemmigrammopetersius , R. loenbergi , R. rhodesiensis and Virilia , is characterized by the following three autapomorphies:

T 1. Supraorbital present (char. 2, 1> 0).

T 2. Posteriorly directed, pointed process on posterior surface of lateral wing of lateral ethmoid present (char. 28, 0> 1).

T 3. Spine-like, medially directed process on medial surface of supracleithrum absent (char. 131, 1> 0).

Figures

Figure 43. Most parsimonious hypothesis of relationships within the Alestidae based on 200 characters. Numbers represent nodes of clades discussed in the text.