Phlebotomine sandflies (Diptera: Psychodidae) constitute a large group of flies, many of which have been described as vectors of leishmaniasis, a disease caused by Leishmania (Kinetoplastida: Trypanosomatidae) parasites. In Tunisia, a total of 17 species belonging to both genera Phlebotomus and Sergentomyia were described. In this work we report on an abnormality found in spermathecae of a female specimen of Phlebotomus (Larroussius) longicuspis Nitzulescu, 1930. Sandflies were collected in SidiSaad locality, in the governorate of Kairouan, central Tunisia, where zoonotic cutaneous leishmaniasis is endemic, during the June to November 2011 period, using CDC light traps. Males were washed and directly identified and females were dissected and morphologically identified using the head and the last two abdominal segments containing spermathecae and ducts. 162 flies were morphologically described. Among 33 females identified as Phlebotomus (Larroussius) longicuspis, one specimen was found abnormal and presented with three spermathecae. An additional spermathecae located in a short bifurcation on the upper extremity of one duct was found. This anomaly is for the first time described in Tunisia. Morphological abnormalities are important to report in order to avoid erroneous sandfly identification or description of new species.