To understand the evolution and speciation of closely related species, a multiple approach encompassing morphological, behavioral, and genetic analyses is necessary. In Korea, three species of Loxoblemmus crickets occur widely. L. campestris and L. equestris are morphologically indistinguishable, whereas males of L. doenitzi are different from the other two species in head morphology. The genetic analyses using the partial mitochondrial COI sequences showed that L. doenitzi diverged off earlier than L. campestris and L. equestris. The analyses of laboratory recordings revealed that distributions of calling song characters generally overlapped among three cricket species. However, the number of pulses in a chirp was two in L. doenitzi and four in L. campestris, but it was greater than or equal to six in L. equestris. Provided that females make mate choice based on this calling song character, the differentiation in this character may lead to premating reproductive isolation and may have evolved during the speciation proccess in these closely related species.

evolution of multicellular organisms. Especially in insects, a large amount of bacterial symbionts are illustrated. Among the insect taxonomic group, sap feeding insects, mostly Heteroptera, that feeds on poor nutrient sources from plants, have developed special organs where symbiotic bacteria can reside. The bacteria mainly provide the host insects with some essential amino acids. This has built evolutionarily unbreakable tie between the symbionts and the their hosts. Here we present an obligate symbiont from Lycorma delicatula (Heteroptera: Fulgoridae) being thought to invade the Korean penninsula recently. Based on the partial 16s rRNA gene sequence, the symbiotic bacterium is identified as Cadidatus Sulcia mullleri. The Genbank data indicates that the bacterium is found in various heteropteran families. This may imply the acquisition of the bacterium precedes the hosts' divergence, though there is an alternative postulation. We discuss its distribution in the sap-feeding insects and potential role on survival of L. delicatula and paratransgenetic application of the bacterium in controlling L. delicatula.

Cryptic species are hardly distinguished by their morphology but reproductively isolated. To understand the evolution and speciation of cryptic species, differentiations between cryptic species should be studied using multiple approaches including morphological analysis. Two of three species under the genus Loxoblemmus in Korea are morphologically similar and may constitute the cryptic species. We studied the differentiations in morphology, calling songs, and genetic sequences to understand patterns of speciation in these three species. Although L.doenitzi was easily distinguished from the other two species based on morphology, the distributions of the number of file teeth and wing morphology overlapped in L. campestris and L. equestris. However, there were clear differentiations in some calling song characters among three cricket species. The number of pulses in a chirp was two in L.doenitzi and four in L. campestris, but that was greater than or equal to six in L. equestris. The genetic sequence analyses using 16S rRNA and COI barcode revealed that L. doenitzi diverged off earlier from the other two species. Calling songs of L. campestris and L. equestris largely differed in spite of their short divergence time. Our results suggest that the speciation processes may involve differentiation in calling songs in the Loxoblemmus complex.

The genus Loxoblemmus has three speices in Korea: L. doenitzi, L. campestris and L. equestris. Males of L. doenitzi have flat heads and triangular horns on both sides of their frons, whereas males of L. campestris and L. equestris have flat heads and no horns. The latter two species are not clearly distinguished based on morphology and thus may constitute cryptic species. We studied the divergence in morphology, calling songs, and genetic sequences to understand patterns of differentiation of these three species. Distributions of the number of file teeth and wing morphology overlapped in L. campestris and L. equestris. In calling songs, the number of pulses in a chirp was four in L. campestris, but that was greater than or equal to six in L. equestris. The genetic sequence analyses using 16S rRNA and COI barcode revealed that L. doenitzi diverged off earlier from the other two species. Thus, the genetic data were congruent with the calling song data in three Loxoblemmus species. Our results suggest that the speciation processes may be closely related to differentiation in calling songs in the Loxoblemmus complex.