Stempellinella fibra, Gilka, Zakrzewska & Krzeminski, 2016
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publication ID |
https://doi.org/ 10.26879/621 |
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publication LSID |
lsid:zoobank.org:pub:BAA44C0D-C497-4CED-85D7-B74A2A2AAEB4 |
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persistent identifier |
https://treatment.plazi.org/id/59790D07-F924-320B-F41E-05F213DDFEDF |
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treatment provided by |
Felipe |
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scientific name |
Stempellinella fibra |
| status |
sp. nov. |
Stempellinella fibra View in CoL
Giłka, Zakrzewska and Krzemiński sp. nov.
Figures 7 View FIGURE 7 , 8 View FIGURE 8
zoobank.org/ 4A5DDD2E-6929-45B8-9652-399D973F1410
Type material. Holotype. Adult male (left fore and left mid leg missing or unobservable, tarsus of right fore leg missing; thorax damaged in part, apices of wings bent and faintly observable) preserved in 18.5 x 15 x 8.5 mm piece of amber ( Eocene , ~40- 45 Ma, Gulf of Gdańsk; CCHH 257-5 ; Figure 7.1 View FIGURE 7 ).
Derivation of the name. From the Latin (fibre, filament), with reference to the strongly elongated filiform hypopygial lamella; noun in apposition.
Diagnosis. Antennal flagellum consisting of 13 flagellomeres (12-13 fused in part). Anal point stout, with strong crests. Superior volsella extensive, bean-shaped, apex broad with distinct protuberances. Stem of median volsella long, club-shaped, bearing slender foliate lamellae, single lamella with strongly elongated filiform tip. Inferior volsella with broad dorsomedian extension at base and apical part distinctly bent medially, covered with long microtrichia.
Description. Adult male (n = 1).
Total length ca. 1.55 mm.
Head ( Figure 7.3, 7.4 View FIGURE 7 ). Eyes bare, small, ovoid, broadly separated by frons. Frontal tubercles conical, ca. 15 µm long ( Figure 7.4 View FIGURE 7 ). Antenna with 13 flagellomeres, 12 of which are readily discernible, flagellomeres 12-13 fused in part, AR 0.68 (when flagellum measured as 12-segmented), AR 0.52 (as 13-segmented); plume fully developed ( Figure 7.3 View FIGURE 7 ). Length of palpomeres 2-5 (in µm): ca. 28, 58, 68, 117. Clypeus with at least 8 setae.
Wing. Slender, with anal lobe weak, broadest at 2/3 length. Sc ending distal of RM. FCu placed distinctly distally of RM; VRCu 1.55. Chaetotaxy and other characters of wing unobservable ( Figure 7.2 View FIGURE 7 ). Legs. Tibial apices with their armature faintly visible. Sensilla chaetica on ta 1 of p 2 not observed. Lengths of leg segments and leg ratios in Table 6.
Hypopygium ( Figure 8 View FIGURE 8 ). Gonostylus short, ca. 60 μm, as long as gonocoxite, slightly arcuate, broadest in proximal part, blunt apex armed with strong apical setae. Anal tergite subtriangular, with several median setae and four-five posterolateral setae on each side of anal point. Anal point stout, reaching slightly beyond apices of superior volsellae, tapering to blunt apex, with strong crests. Superior volsella extensive, bean-shaped, apex broad with distinct protuberances bearing two fine setae. Digitus not observed. Stem of median volsella long (ca. 30 µm), club-shaped, bearing several setiform and four slender foliate lamellae, including single foliate lamella with extraordinarily elongated filiform tip ( Figure 8.3-5 View FIGURE 8 ). Inferior volsella reaching 3/4 length of gonostylus, with broad dorsomedian extension at base, posteriorly directed, with apical part distinctly bent medially, covered with long microtrichia (distinctly visible on median margin), bearing several strong setae.
Remarks. Among all the described Stempellinella species, both fossil and extant, S. fibra is distinguished by a combination of extraordinarily structured hypopygial volsellae. The best diagnostic character is the robust median volsella, consisting of a club-shaped stem armed with several slender foliate lamellae, one of which is strongly elongated into a filiform tip ( Figure 8.5 View FIGURE 8 ). A slightly similar but smaller median volsella is observed in S. ciliaris ( Goetghebuer, 1944) , the comparatively long but sinuous stem is known from S. coronata Inoue et al., 2004 , whereas similarly long but setiform lamellae - from S. lamellata Ekrem, 2007 ( Ekrem, 2007, figures 9, 11, 19). The inferior volsella covered with long microtrichia, with the broad dorsomedian extension at base found in S. fibra , is also a diagnostic structure unknown from either extant or fossil Stempellinella . The tendency towards the formation of a fully developed antenna (13 flagellomeres) observed in other fossil Stempellinella (cf. Zakrzewska and Giłka, 2014, 2015a) is now confirmed in S. fibra ( Figure 7.3 View FIGURE 7 ).
A list of Stempellinella species recently presented ( Zakrzewska and Giłka, 2015a) is now extended with S. fibra and complemented with S. depilisa Guo and Wang, 2007 from China, thus comprises 20 extant species worldwide and four extinct species described from ambers of the Baltic region.
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