Incomplete Speciation Research Articles

The cypridinid copulatory limb and a new genus Kornickeria (Ostracoda: Myodocopida) with four new species of bioluminescent ostracods from the Caribbean

Kornickeria , a new genus of myodocopid ostracod (Cypridinidae) in the Caribbean Sea, is described in terms of morphology and species-specific bioluminescent display patterns. Four new species are described: Kornickeria louisi , the type species for the genus, K. coufali, K. marleyi and K. hastingsi , which includes two subspecies: K. hastingsi hastingsi and K. hastingsi carriebowae . Vargula bullae is reassigned to Kornickeria with a supplementary description. Of the new species, the first three are known only from Jamaica and the last from Jamaica, Belize and Roatan. All are found primarily among shallow coral reef habitats where the males produce vertical trains of luminescent secretions as species-specific courtship patterns. Kornickeria is defined by several derived morphological characters, but species differ more in luminescent displays than morphology. Displays are restricted to upward and downward variations of vertical displays and consist of a shortening phase of a few bright pulses and a longer trill phase of dimmer, fairly closely and evenly spaced pulses. Train lengths are relatively short compared to those of many other Caribbean signalling species. Both the described (5) and undescribed (c. 12) species of Kornickeria known thus far are confined to the Caribbean Sea, but the genus is distributed more widely within the Caribbean than the other signalling cypridinid clades. Kornickeria species have been found in all Caribbean sampling localities except Panama where they are apparently replaced by their sister clade, the Z-Group. The slight non-clinal geographic variation (as well as the behavioural variation of one population) exhibited in the most shallow-dwelling species, K. hastingsi , may reflect (1) the presence of morphologically and behaviourally cryptic species, (2) unexpected and unexplained dispersal abilities and/or (3) current but incomplete speciation processes. The paired male copulatory organs are an eighth pair of ostracod limbs, which bear many useful systematic characters. A general plan, which we here produce as a model, applies to the limb throughout the family Cypridinidae. Homologies within the Cypridinidae were found for many copulatory characters, particularly the setae, ornamentation, lobe shapes and internal sclerites. Articulation of internal sclerites marks separation of the limb into two articles. Three lobes extend from the limb: two (inner and central) from the basal article and one (outer) from the distal article.

Five-Way Hybridization of Varied Sittellas Daphoenositta chrysoptera (Aves : Neosittidae) in Central Queensland

Five-way hybridization is documented in the varied sittella in central Queensland, involving all Australian forms: Daphoenositta chrysoptera leucoptera, D.c. striata, D.c. leucocephala, D.c. chrysoptera and D.c. pileata. For the first time, gene flow is demonstrated between striata and leucoptera, based upon breeding specimens from the region of Longreach and Barcaldine. At least 10 different morphological characters appear to segregate and recombine independently, including an extension of the wing bar into the secondaries which, described here for the first time, is present in the three 'orange-winged' forms but not in 'white-winged' leucoptera and striata. The evidence presented supports the view that all Australian sittellas are conspecific. Historical factors are invoked to explain divergence, hybridization and incomplete speciation in this complex.

On the number of Patella species in south-west England

Limpet populations of the genus Patella from the south-west coast of England were examined by means of gel electrophoresis in order to settle debate on the specific status of the three Patella forms. Populations varied morphologically along an east-west gradient, from three distinct forms in the west to continuous intergradation in the east, in accord with earlier studies. Patella collected were divided into three groups on the basis of a complex of external features described by earlier workers, corresponding to the morphologically defined taxa P. vulgata Linn., 1758, P. aspera Röding, 1798, and P. depressa Pennant, 1777. These groups were electrophoretically distinct in five of seven enzyme systems examined, with no hybrids or intermediates. Incomplete speciation and hybridization can be ruled out as possible causes of the observed morphological variation.