Myxia, Bahder & Bartlett & Barrantes Barrantes & Zumbado Echavarria & Humphries & Helmick & Goss & Ascunce, 2019
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publication ID |
https://doi.org/ 10.11646/zootaxa.4701.1.5 |
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publication LSID |
lsid:zoobank.org:pub:5E803236-44AC-4228-A442-72AAD7F32C8A |
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persistent identifier |
https://treatment.plazi.org/id/03A087FE-FFAF-AE67-AEDF-64D3F9FDFB50 |
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treatment provided by |
Plazi |
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scientific name |
Myxia |
| status |
gen. nov. |
Myxia gen. n.
Type species. Myxia belinda sp. n. by monotypy and current designation.
Diagnosis. Myxia gen. n. possesses lateral pronotal carinae terminating on the ventral margin of the prothorax, a character shared with Myndus but lacks the denticle of the forecoxae ( Fig. 2 View FIGURE 2 ), a feature shared with Haplaxius . Tegulae evident and tibiae of hind legs lack spines (tribal feature of Oecleini ). The genus Myxia gen. n. can be diagnosed from Haplaxius and Myndus by the overall form of the gonostyli. In Myxia gen. n., the gonostyli appear distally bifid, possessing a dorsal process near the terminus of each gonostylus in lateral view pointing dorsad and in ventral view, and a lateral tooth on the inner margin with an acute apex. In addition, medioventral process of pygofer is subtriangular. Phallobase separated from aedeagus.
Description ( Figures 4–9 View FIGURE 4 View FIGURE 5 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 ). Head much narrower than pronotum, weakly projecting in front of eyes. Vertex much wider than long, approximately quadrate, lateral margins foliate, disk concave, median carina weak posteriorly, obsolete anteriorly. Fastigium rounded, frons approximately triangular, widening to frontoclypeal suture, median carinae present. Clypeus inversely triangular, narrowed to labrum. Pronotum very narrow, tricarinate, carinae reaching posterior margin; paradiscal region nearly exceeding antennae. Mesonotum broad and longer than vertex+pronotum, tricarinate; scutum and scutellum distinctly separated by inflection. Tegulae evident, without carinae. Coxae of front leg without ventral denticles. Fore femora lacking denticle. Tibiae of hind legs lacking spines. Wings transparent, macropterous, well-exceeding apex of abdomen. Abdomen weakly compressed. Pygofer in lateral view roughly triangular, widest ventrally; ventral margin of pygofer opening bearing elongate subtriangular projection. Gonostyli elongate, distally bearing apical and subapical tooth (at least in type species), giving a broadly bifid appearance. Anal tube broad, distally enlarged, relatively short (sensu Kramer 1979); anal column elongate. Aedeagus simple bearing small apical flagellum, phallobase surrounding aedeagal base and projecting caudally to subtend aedeagus, bearing multiple elongate projections.
Remarks. In the field, the specimen was tentatively identified as Haplaxius due to overall similarity in structure and general habit. More careful morphological examination seemed to confirm generic placement. The general form and behavior of this taxon appeared to coincide with Haplaxius . While differences in terminalia set this species apart from other Haplaxius , it was molecular characterization that made it apparent that observed differences merited genus level designation.
A difference that appears to set Myxia n. g. apart from Haplaxius , is that in Myxia , the phallus consists of the phallobase that surrounds the base of the aedeagus and projects beneath to subtend it, whereas in Haplaxius , the phallobase envelopes the aedeagus forming a phallotheca. The variation in degree to which the phallobase surrounds the aedeagus in Myxia cannot be discerned from the single species described here, but this character appears to be an important difference among the genera.
The form of the gonostyli also appears different among the genera. The general form of gonostyli in Haplaxius senso stricto is that of a larger, globular apex in ventral view and in lateral view, the rounded apex is generally visible but usually angled upward. However, many Haplaxius deviate from this morphological type. The illustrations of the type species H. laevis Fowler, 1904 ( Kramer 1979, figs. 159–162), terminalia exhibit a rounded terminus of the gonostyli in both ventral and lateral views. Haplaxius crudus have the same general form of the gonostyli and aedeagus as H. laevis and provided a useful comparison ( Fig. 3 View FIGURE 3 ). The structure of the terminalia of H. crudus appears to be comparable to that of H. laevis and serves as a useful morphological template for comparison. Caldwell (1946) also considered H. crudus (as Paramyndus cocois ) similar enough based on general body structure to H. laevis to place them in the same genus, suggesting that there were other species that appeared more distinct from H. laevis than H. crudus . It had previously been suggested that Haplaxius (as Myndus ) “...could be subdivided into a series of genera or subgenera; these divisions would be based primarily upon structural features or variations in the pattern of the male genitalia, especially the aedeagus.” Kramer (1979: 302). This represents the first genus-group to be erected associated with Haplaxius based on molecular data and morphology. One other species of Haplaxius , H. delta , according to Kramer (1977) possesses a similar form for both the gonostyli (bifurcated with dorsal process angled dorsad) and medioventral process (subtriangular). Also, the aedeagus is simple with hooked flagellum and phallobase bearing large processes according to Kramer (1979; Fig. 175–179). Based on the overall similarity of the terminalia to the novel taxon we propose H. delta be moved to the novel taxon, bringing the species number for Myxia gen. n. to two species.
Etymology. The generic name is an arbitrary amalgamation of Haplaxius and Myndus suggestive of the similarities of Myxia to both genera. The genus name is feminine in gender.
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