Genus-level revision of the Heterozerconoidea (Parasitiformes: Mesostigmata) Author Klompen, Hans klompen.1@osu.edu Author Gerdeman, Beverly S. klompen.1@osu.edu text Zootaxa 2023 2023-07-28 5322 1 1 66 http://dx.doi.org/10.11646/zootaxa.5322.1.1 journal article 10.11646/zootaxa.5322.1.1 1175-5326 8203657 DD295EE6-AB3F-4377-900E-CC76F1C6BC2D Narceoheterozercon Gerdeman & Klompen 2003 Narceoheterozercon Gerdeman & Klompen 2003: 352 [ type species: Narceoheterozercon ohioensis Gerdeman & Klompen 2003 , by original designation]. Diagnosis. Spermatodactyl long, recurved, and largely smooth (7, except in Narceoheterozercon ex Alabama-C); anterior dorsal setae j1 minute (<5 µm) (28.2); sternal lyrifissures iv 1 in adults absent (44); sclerotized areas near sternal setae st2 and st 3 in male completely fused (51.0); females with prominent, well sclerotized, solenostomes arching anteriorly from the antero-median corner of the ventral opisthosomal suckers (64, except in Narceoheterozercon ex Alabama-C); setae S 5 in adults minute (75), all marginal opisthosomal setae setiform (77, reversal); femora I seta pl2 absent (85), femora II seta pv in males setiform (108, reversal); remaining setae on legs II of male all setiform. FIGURES 8–11 . Heterozerconidae , chelicera males, photograph (top) and composite drawing (bottom): 8–9, Amheterozercon amphisbaenae (OSAL 052760); 10–11, Narceoheterozercon ohioensis (OSAL 001221). Remarks. The diagnosis of the genus by Gerdeman & Klompen (2003) included four characters: 1) female with prominent, well sclerotized, solenostomes arching anteriorly from the antero- median corner of the ventral opisthosomal suckers (64.2); 2) male with long, recurved, and largely smooth spermatodactyl (7.2); 3) male lacking prominent spines on legs II (107–110); 4) adults lacking spine-like marginal opisthosomal setae (77). Of these, characters 1and 2, while unique, are not shared by some taxa included in the genus in this study (e.g., population Alabama-C). As a result, the diagnosis (and support) for this genus is not strong. Data on additional species may help clarify the concept of this genus. Most Narceoheterozercon species have secondary genital openings (solenostomes) in the female ( Gerdeman 2002 ). These are located at the antero-internal corners of the opisthogastral suckers and continue internally in the form of sclerotized tubes ( Fig. 61 , arrow). Evidence that these tubes serve as secondary genital openings includes the observation that these structures are limited to the females, and the observation of a broken-off spermatodactyl in one of the tubes ( Fig. 52 ).