Labriella, Namyatova & Cassis, 2021

Namyatova, Anna A. & Cassis, Gerasimos, 2021, Five new genera of the subfamily Cylapinae (Insecta, Heteroptera, Miridae) from Australia, ZooKeys 1012, pp. 95-134 : 95

Labriella gen. nov.

Type species.

Labriella fusca sp. nov. by original designation.

Diagnosis.

Labriella is distinguished from other Cylapinae by the following combination of characters: labrum longer than labial segment I, oval, flattened at sides (Fig. 5D, E ); head vertical with antennal fossa located above mandibular plate (Fig. 5A ); eye not pedunculate; vertex carinate, concave (Fig. 5B, C ); eye covering anterior angle of pronotum (Fig. 5A, B ); buccula not ring shaped, declivous posteriorly (Fig. 5A ); total antenna length shorter than body with antennal segment II as thick as segment I, segment IV longest (Fig. 5D ); apex of labium reaching abdominal segments IV-V; labial segments I and II not subdivided (Fig. 5E ); collar very narrow, delimited with deep depression (Fig. 5B ); mesepimeral apodeme slit-like; mesothoracic spiracle with microsculpture along anterior margin dorsally (Fig, 5H); corium with ridge along medial fracture (Fig. 5I ); impunctate brown body, covered with semi-adpressed setae; pronotum and hemelytron not constricted; hemelytron not modified or shortened (Figs 1 , 5I ); femora not significantly enlarged (Fig. 5K ); parempodia setiform (Fig. 5F ).

Description.

Male. Coloration (Fig. 1 ). Mainly dark brown, for details see description of the species. Surface and vestiture. Dorsum and pleura glabrous, mostly matte, without punctation or rugosities (Fig. 5B, I, H ); scutellum not serrate laterally (Fig, 5I); pleura with net-like pattern of microsculpture (Fig. 5H ); body clothed with dark semi-adpressed setae, shorter than antennal segment II width, those setae shorter on appendages and almost absent on pleura (Fig. 5B, I, H ). Structure. Head. In dorsal view head wider than long, vertical, vertex concave and carinate; eye covering anterior part of pronotum, not protruding (Fig. 5B ); in anterior view head wider than high; antenna attached near ventral one third of eye, above ventral margins of eye; clypeus separated from frons by depression, its base placed slightly below antennal fossae, but above inferior margin of eye (Fig. 5C ); in lateral view head ca. 1.5 × as high as long; eye slightly upraised above vertex, covering lateral margins of pronotum; distance from eye to ventral side of head subequal to third part of eye height laterally; eye covering anterior angles of pronotum; antennal fossa placed slightly above mandibular plate, adjacent to eye; mandibular and maxillary plate separated from head by distinct suture posteriorly; buccula twice as long as high, declivous posteriorly, not ring-like, almost reaching posterior margin of head (Fig. 5A ); labrum as long as labial segment I, oval and flattened (Fig. 5D, E ). Antenna (Fig. 5D ). Total length shorter than body; segment I subequal to vertex width; segment II as wide as segment I, cylindrical and not incrassate apically; segment III and IV filiform, narrower than segments I and II; segment III subequal to half of segment II; segment IV ca. 2.5 × as long as segment III. Labium (Fig. 5D, E ). Reaching abdominal segments IV-V, segments not subdivided; labial segment I slightly surpassing base of forecoxa; segments I, II and III subequal in length, segment IV subequal to half of segment III. Thorax. Pronotum wider than long; collar delimited, very narrow, narrower than antennal segment I (Fig. 5B ); lateral margin of pronotum in dorsal view straight (Fig. 5B ), in lateral view angulate, but not carinate (Fig. 5A ); posterior margin of pronotum bisinuate (Fig. 5B ); calli slightly upraised, occupying 2/3 of pronotum; calli separated with shallow depression between them; scutellum flat; mesoscutum exposed (Fig. 5I ); propleural apodeme mostly straight, apical part inclined anteriorly (Fig. 5A ), mesothoracic apodeme slit-like; mesothoracic spiracle open, slit-like, with small area of microsculpture along anterior margin dorsally; metathoracic gland evaporative area triangular, lateral margin reaching base of hind coxa; peritreme noticeably upraised, rounded, matte; metepimeron narrow (Fig. 5H ). Hemelytron. Slightly narrowed anteriorly, and widened posteriorly; longitudinal ridge on clavus present, distinct; claval commissure almost twice longer than scutellum; medial fracture distinct, surpassing middle of corium; ridge along medial fracture present, surpassing middle of corium; embolium mostly narrow, apically widened, its width subequal to 1/6-1/7 of cuneus width at base (Fig. 1 ); R+M almost indistinct on posterior part of corium (Fig. 5I ); cuneus delimited with pronounced incision, longer than wide; membrane with two cells (Fig. 5J ). Legs. Forecoxa slightly longer than pronotum, slightly longer and as wide as middle and hind coxae; forefemur widened, approximately the same width as hind femur, each of them wider than middle femur (Fig. 5K ); tarsus three-segmented, segment I and III subequal in length; segment II slightly longer than each of them; suture between segment II and III weak (Fig. 5G ); claw with subapical tooth, middle row of tiles on unguitractor distinct, not reduced (Fig. 5F ). Genitalia. See description for species.

Female. Similar to male, but antennal segment II wider and shorter. Genitalia. See species description.

Etymology.

The genus is named for its enlarged labrum. The gender is feminine.

Remarks.

Labriella cannot be confidently placed to any of the Cylapinae tribes based on the current classification and diagnoses ( Gorczyca 2000). The combination of the vertical head, carinate vertex, antennae shorter than the body and the presence of the ridge along the medial fracture occurs in all representatives of Bothriomirini ( Namyatova et al. 2019). However, bothriomirines are distinctly punctate, their labium not reaching the abdomen, they have a collar not delimited or shallowly delimited, the mesopleural apodeme round, and their mesothoracic spiracle without microsculpture. All those character states are absent in Labriella (see Diagnosis).

Labriella is similar to all Fulviini in that the total antennal length is shorter than the body, antennal segment II is as thick as segment I, and the labium is relatively long, the apex is reaching abdominal segments IV-V. However, Labriella differs from other Fulviini representatives in the possession of a vertical head (Fig. 5A ), whereas in Fulviini it is mainly horizontal ( Gorczyca 2000). Additionally, in all examined representatives of Fulviini the antennal fossa is located near the suture between the mandibular and maxillary plates (e.g., Figs 8F , 11C , 13I , see also Wolski 2010; Wolski et al. 2017, 2018; Namyatova and Cassis 2019a for more SEM images of Fulviini heads), whereas in Labriella it is located just above the mandibular plate (Fig. 5A ).

Labriella fits many characters provided for the Cylapini diagnoses by Wolski (2017), e.g., the vertical head (Fig. 5B ), labial segments I and II not subdivided (Fig. 5E ), and the collar delimited with deep depression (Fig. 5B ). However, some characters of Labriella do not fit the diagnoses. For example, in Cylapini , the anterior portion of the vertex is perpendicular to the rest of the vertex, the buccula is ring-like, the ventral margin of the eye barely reaches or does not reach the mandibular plate, and the antennae are thread-like. Whereas in Labriella the vertex is sloping more or less gradually, the eye reaches the maxillary plate, the buccula is not ring-like (Fig. 5A ) and the antennae are not thread-like (Fig. 5D ). We place Labriella into Cylapini based on the shared vertical head character. Based on the personal observations and the literature, all genera of Cylapini have this type of head, whereas the head is horizontal or sub-horizontal in all examined Fulviini and all other characters vary within both tribes.

Among species of Cylapini , Corcovadocola and Cylapoides Carvalho, 1952 are most similar to Labriella with the eyes being at least slightly covering the anterior angles of the pronotum and the antennal length being shorter than the body. Cylapoides differs from the new genus in the eyes being slightly pedunculate, the labium reaching the hind coxae and the body covered with erect setae ( Carvalho 1952). Corcovadocola differs in having a brachypterous female, the vertex being only slightly concave and the lateral margins of pronotum being slightly emarginate ( Carvalho 1948). The structure of the labrum was not included in the initial descriptions for all the above-mentioned genera ( Poppius 1913; Carvalho 1948, 1952, 1986).

Labriella may be similar to the Neotropical genus Tucuruisca Carvalho, 1986 placed within the Fulviini and known only from the initial description. It also has a vertical head and the long labium, and its antennae are shorter than the body. According to the image, the eyes in Tucuruisca are also large, and are placed very close to or even slightly covering the anterior angles of the pronotum. Tucuruisca differs from Labriella in possessing a body covered with long erect hairs, the antennal segment IV being shorter than segment II and the thickened hind femora ( Carvalho 1986).

Figures

Figure 1. Habitus of Dariella rubrocuneata and Labriella fusca.

Figure 5. SEM images. Labriella fusca A head and pronotum, lateral view B head and pronotum, dorsal view C head, anterior view D antenna E labium F pretarsus, ventral view G hind tarsus H pleura I scutellum, clavus and corium J cuneus and membrane cell K legs L trichobothria on middle femur M trichobothria on hind femur.

Figure 8. SEM images. Callitropisca florentine A head, anterior view B cuneus and membrane cell C apical part of labial segment II D head and pronotum, dorsal view E pleura F antenna G head and pronotum, lateral view H labium I labial segment I J scutellum, clavus and corium K tubercles on hemelytron L pretarsus, ventral view M pretarsus, dorsal view.

Figure 11. SEM images. Laetifulvius morganensis A head, anterior view B head and pronotum, dorsal view C head, lateral view D labial segments I and II E labial segment I F apical part of labial segment II G legs H scutellum, clavus and corium I cuneus and membrane cell J pleura K antennal segments I and II L hind tarsus M pretarsus, ventral view N pretarsus, dorsal view.

Figure 13. SEM images. Micanitropis seisia A head, anterior view B tubercles on hemelytron C labial segment I D apical part of labial segment II E head and pronotum, dorsal view F cuneus and membrane cell G trichobothria on middle femur H trichobothria on hind femur I head and pronotum, lateral view J pleura K antennal segments I, II L pretarsus, ventral view M scutellum, clavus and corium N legs O hind tarsus P pretarsus, dorsal view.