First record of Spirocamallanus krameri (Nematoda: Camallanidae) in Brazil: Morphological review

Abstract This study aimed to describe the occurrence, morphology and prevalence of Spirocamallanus krameri, a parasite of Hoplerythrinus unitaeniatus collected in state of Pará, Brazil. The morphological and morphometric characteristics are consistent with the species S. krameri, by having a hexagonal mouth opening, 16 cephalic papillae and two lateral papillae on the amphids. The buccal capsule is internally different in both sexes, with (11–13) spiral ridges in males and (13–17) spiral ridges in females. The basal ring is well developed, and three teeth are present in males and absent in females. Ten sessile caudal papillae and a pair of phasmidial pores occur in males. The spicules are small, subequal, 81–101 µm in length and the tail is tapered. The vulva in females is postequatorial, the tail is conical with lateral phasmidial pores. Among the species of Spirocamallanus that have short spicules, the general morphology of S. krameri most resembles that of S. inopinatus, but differs from that species, which have two cephalic teeth visible (absent in S. krameri) and specimens of S. inopinatus do not have sexual dimorphism in the buccal capsule of present in S. krameri.

摘要 本研究旨在记述巴西帕拉州采集的带纹梭口脂鲤（Hoplerythrinus unitaeniatus）体内寄生的克拉默旋驼形线虫（Spirocamallanus krameri）的存在情况、形态特征及感染率。该线虫的形态及形态计量学特征与克拉默旋驼形线虫（S. krameri）相符，具体表现为口孔呈六边形，具16个头乳突，且侧感器（amphids）上带有2个侧乳突。雌雄虫的口囊内部结构存在差异：雄虫具11~13条螺旋嵴，雌虫则具13~17条螺旋嵴。口囊基环发育良好，雄虫具3枚齿，雌虫则无齿。雄虫具10个无柄尾乳突以及1对尾感器孔（phasmidial pores）。交合刺细小且近等长，长81~101 μm，尾部呈锥形。雌虫的阴门位于体后赤道区之后，尾部呈锥形且带有侧生尾感器孔。在具短交合刺的旋驼形线虫属（Spirocamallanus）物种中，克拉默旋驼形线虫的整体形态与意外旋驼形线虫（S. inopinatus）最为相似，但二者存在显著差异：意外旋驼形线虫具2枚可见的头齿（克拉默旋驼形线虫无此特征），且意外旋驼形线虫的口囊不存在克拉默旋驼形线虫所具有的雌雄二态性。