Ontogenetic change of distributional patterns of pore systems in Cythere species and its phylogenetic significance

Abstract

Species of Cythere (Ostracoda, Crustacea) have about one hundred normal pore systems on each valve of the carapace. These can be classified into five types on the basis of morphological features. They were examined in the light of intraspecific variation and interspecific difference. Each of the five pore systems has its own mode of ontogenetic increase in number. Comparison among fourteen Cythere species shows that the distributional patterns are completely identical in the A‐3 stage, but that they are classified into four and eight groups in the A‐2 and A‐1 stages, respectively. In the adult stage the pattern becomes diversified among the fourteen species, though homologous relationships are still recognized between different species. The similarity and difference of the pore patterns, which are traceable until the last ontogenetic stage, can be used to determine phylogenetic relationships. These findings were applied to the reconstruction of phylogeny of the eleven living and three extinct species of Cythere.□Crustacea. Ostracoda, Cythere, Ontogeny. Phylogeny, pore system, pore canal. speciation, laroal morphology.

Phylogeny and evolution of Loxoconcha (Ostracoda, Crustacea) species around Japan

“…The phylogenetic reconstruction of Ostracoda by the analysis of the carapace pore-systems (i.e., a pore with a bristle) was first proposed and exemplified by Tsukagoshi (1990). He examined 14 Cythere species, and concluded that the interspecific differentiation in distributional patterns of poresystems on the carapace for later instars (A-2, A-1 and adult) reflected the phylogeny of the genus Cythere.…”

The History of Sexual Dimorphism in Ostracoda (Arthropoda, Crustacea) Since the Palaeozoic

“…His work was followed by [26] [62][63][64] for species of other genera. This method of phylogenetic reconstruction, proposed by [21], was termed 'differentiation of distributional pattern of pore (DDP) analysis' [61]. The pore distribution in L. kamiyai was examined by this method [16], and the results were compared to the pore data of 17 other Loxoconcha species (Figure 16).…”

“…The number, distribution, and differentiation of pores on the ostracod carapace surface during ontogeny have been studied to determine phylogenetic relationships among species [61]. The reconstruction of ostracod phylogeny based on pore analyses was first proposed by [21] for 14 species of the genus Cythere. His work was followed by [26] [62][63][64] for species of other genera.…”

“…The word ostracod (or 'ostracode') is derived from Greek word 'ostrakon', which means 'a shell'. This carapace (or shell) has various morphological characteristics (Figures 1 and 2) that allow detailed taxonomic and phylogenetic studies to be performed on both living and fossil specimens [20][21][22].…”

The coelotrich: form and function of an unusual sensillum inLowrya(Ostracoda: Myodocopina: Cypridinidae)

“…These extend from the valve surface through pore canals, and are serviced by dendrites within the noncalci¢ed inner lamella of the carapace (Tsukagoshi 1990). Apart from marginal pore canals, the remaining normal pore canals are distributed over the entire carapace surface.…”