Eualus heterodactylus sp. nov., a new hippolytid shrimp from Chinese coast of the Yellow Sea （Crustacea,Decapoda, Caridea）

A new species from the caridean family Hippolytidae, Eualus heterodactylus sp. nov. is described and illustrated based on the specimens collected from Chinese coast of the Yellow Sea. The new species is a part of an informal species group characterized by the possession of epipods on the anterior three pairs of pereopods, and is distinguished from other species of this group by the dactyli of the third to fifth pereopods possessing distinctly stair-like flexor margins in males.     

Sympatric seagrass shrimp show similar structure and selection along the seashore: a comparison of two cryptic Phycomenes zostericola lineages

Small crustaceans are diverse and abundant in seagrass habitats and provide many ecological services. Further information is needed about their long‐ and short‐term response to habitat fragmentation and loss. Shrimp specimens were sampled from coastal seagrasses: latitudes 9°–27° S (Torres Strait to Moreton Bay, Queensland, Australia) and longitudes 141°–153° E (Weipa to Moreton Bay, Queensland, Australia). The seagrass shrimp Phycomenes zostericola (Caridea: Decapoda) underwent phylogeographic analysis using mitochondrial and nuclear sequence data. Lineage relationships were investigated and two deeply divergent sympatric lineages of P. zostericola were discovered in northern samples. The two lineages display vastly different demographic histories in spite of similar overall phylogeographic patterns. The two lineages appear to be in secondary contact with each other, detailing independent histories of sea level change, long distance colonisation and habitat fragmentation. Their regional structure is evidence that the potential for dispersal is only realised under specific environmental conditions. Nuclear data, used to determine reproductive status between lineages, instead displayed a non‐random latitudinal geographic distribution suggesting directional selection, possibly in response to ocean temperatures. The differences between the two deeply divergent lineages highlight the importance of understanding variability among cryptic taxa and their response to habitat change.     

日本沼虾精子在真虾部Caridea生殖进化中地位的研究

用透射电镜技术研究了日本沼虾成熟精子的形态结构,并和真虾部其它动物及对虾部的精子结构作了比较分析,初步探讨了日本沼虾的进化地位。具备丝状核物质和泡状核物质是日本沼虾成熟精子的重要特征之一,真虾部精子的细微结构可以作为分类依据。日本沼虾精子顶体结构较对虾部简单,在系统进化上,可能处于较低的地位。