Two new curved species and a new record of a straight species are reported; neither new species has the craticular bars seen in the generitype. C. desportesiae resembles C. guamensis and C. riddleae in size and number of plastids (2 pairs) but has much finer striae (46–50 in 10 µm). C. leandrei has multiple plastids and is very long, like C. koenigii but more slender and with rectangular rather than circular areolae. Valvocopulae of this species are described for the first time in Climaconeis spp., which otherwise show no distinction among copulae. A straight species, provisionally identified as C. scalaris, is reported for the first time from tropical waters. An updated key to the 18 known species is provided.