Mucronia fjellbergi, Potapov & Babenko, 2014
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publication ID |
https://doi.org/ 10.1080/00222933.2014.908971 |
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publication LSID |
lsid:zoobank.org:pub:D2A206F3-F51B-479B-8930-2A7DC7522412 |
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persistent identifier |
https://treatment.plazi.org/id/945AF5EC-C744-42CB-AC3B-ACE14E777C8B |
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taxon LSID |
lsid:zoobank.org:act:945AF5EC-C744-42CB-AC3B-ACE14E777C8B |
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treatment provided by |
Felipe |
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scientific name |
Mucronia fjellbergi |
| status |
sp. nov. |
Mucronia fjellbergi View in CoL sp. nov.
( Figures 1–3 View Figure 1 View Figure 2 View Figure 3 )
Type material
Holotype: female, Russia (Far East): Magadan Region, upper reaches of Kolyma River, Bol’ shoi Annachag Mts. Range, Aborigen field station, ~ N 61.93°, E 149.67°, thick moist moss in rock crevices, 1600 m alt., 23.07.1979, leg. A. Fjellberg ( AF 64 / 79) (deposited in MSPU). GoogleMaps
Other material
Fifteen specimens, same data as holotype, 1550 m alt. ( AF 65 /79) GoogleMaps .
Description
Body size 1.3–1.5 mm (adult male and subadult females on slides). Habitus as common for subfamily Isotominae , with long cylindrical furca. Body dark purple, ventral side of abdomen paler, legs and furca almost unpigmented. Head mostly white with large dark spot connecting eye fields and bases of antennae. Posterior half of head with more diffuse medial spot. Mouth cone darker. Antennae pigmented, darker in distal half ( Figure 3B View Figure 3 ). Abd.V–VI not fused. 6 + 6 large ocelli. PAO larger than ocellus (1.3–1.5) and 0.4 as long as Ant.1 width, roundish, with five lobes and slightly swollen mid-section ( Figure 1B View Figure 1 ). Antennal chaetotaxy of common nature: Ant.1 with 4–6 thin and long and 2 short sensilla, Ant.2 with about 10, and Ant.3 with 15–25 thin sensilla. Ant.3 organ with two mid-sized sensilla ( Figure 1I View Figure 1 ) and ventrolateral spine-like sensillum. Ant.4 with simple pin-seta and roundish organite ( Figure 1H View Figure 1 ). Labrum with 5,5,4 papillate setae, 4 prelabral setae, anterior edge with four sharp ridges ( Figure 1F View Figure 1 ). Ventroapical ciliation complex, with several rows of cilia. Frontoclypeal field with many setae. Maxillary outer lobe with trifurcate palp and 4 sublobal setae. Labial palp with all papillae A, B, C, D and E unmodified ( Figure 1C View Figure 1 ). Guard setae of papillae A–D as common for the family, papilla E with 8 guards, an additional guard (e2’) set together with e2 and e3, on inner side of labium ( Figure 1D,E View Figure 1 ). Terminal setae of papillae short, not longer than surrounding guard setae. Six proximal setae present. Hypostomal papilla as common for family, unmodified. Basal fields of labium with 6 median and 5 lateral setae ( Figure 1C View Figure 1 ). Postlabial setae 4–6 on each side. Mandibles normal for the family, with strong molar plate. Maxilla unmodified, with 6 lamellae and strong tridentate unguis, Lam.1 pointed, lingua-shaped, with very weak denticles ( Figure 1G View Figure 1 ).
Body covered with numerous smooth, expanded setae of different lengths ( Figure 3A View Figure 3 ). Macrochaetae strong and ciliate, 1,1/3,3,3,3,5 in number on Th.II– Abd.V. Longest macrochaetae on Abd.V–VI 3.9–4.5 as long as inner length of unguis 3 and 1.1–1.3 as long as Abd.V length. Sensilla long and thin. Sensillary formula as 6–7,7–8/6–7,6,6–7,~8,>7(s), microsensilla (ms) as 1,1/0,0,1. On Abd.I–III accp-s in p-row, on other segments their positions float: in front of or, more rarely, in p-row. Most lateral accp-sensilla on Th.II–Abd.III shorter than others (noted as ‘short s’ in Figure 1A View Figure 1 ). Sensilla of Abd.IV shorter than on other segments. Two lateral sensilla on Abd.V slightly thicker than others.
Ventral tube with 5–7 + 5–7 lateral (distal) setae, 3–4 + 3–4 frontal and 6–8 caudal (posterior) setae, including a pair in distal position. Retinaculum with 4 + 4 teeth and 3–6 setae on corpus. Manubrium with many dorsal and ventral setae ( Figure 2B View Figure 2 ). Setae along lateral edge of manubrium ciliate, apical thickening with blunt teeth, ventroapical setae 2–3 + 2–3. Dens cylindrical, with noticeable bend medially, anteriorly with numerous setae, posterior side with 20–23 setae ( Figure 2A,C View Figure 2 ). Distal half of dens crenulated posteriorly, usually with 3 outer, 3 inner and 2 posterior setae ( Figure 2C View Figure 2 ). Basal half of dens almost smooth, with 12–14 setae (exact number of posterior setae is uncertain because there is no clear gap between them and anterior setae at dens base). Two setae at base and one at the middle straight and stronger than others. Mucro strong, with six teeth, long inner lateral lamella running from subapical tooth to base, and two thick lateral setae, thin and curved at apex ( Figure 2D,E View Figure 2 ). Ratio manubrium: dens: mucro as 3.9–4.7: 5.5–6.4: 1. Tibiotarsi with 11 apical setae (A1–7, T1–4). Outer side of tibiotarsi of leg 2 and 3 with ciliate macroseta. Tibiotarsi 3 with erect, smooth, stiff seta at the middle of inner side ( Figure 2F View Figure 2 ). Unguis of normal shape, without inner teeth, with lateral teeth. Unguiculus pointed, with inner tooth ( Figure 2F View Figure 2 ). Basal parts of legs and furcal subcoxa include several large ciliate macrosetae ( Figure 1A View Figure 1 ). Reproductive males with genital papillae as common for the family.
Remarks
To date Mucronia was a monotypic genus, with the only known species Mucronia enigmatica Fjellberg described from the surface of melt-water ponds near Mendenhall Glacier in the Juneau Icefield, Alaska. Fjellberg (2010) mentioned two characters which separate Mucronia from other genera of the family: ‘ a clearly lobed PAO and a mucro bearing more than one seta ’. The new species from NE Asia described above also has slightly lobed PAO and elongated mucro with two setae, and so also belongs to this unusual genus sharing characters of Isotomidae and Tomoceridae . The cylindrical and sharply bent dens is also very characteristic of the genus. Mucronia fjellbergi sp. nov. differs from the type species of the genus in its unmodified mouth parts and tibiotarsi, long ciliate macrochaetae, and more setae on furca. Mucro of the new species is even more similar to that of Tomoceridae because of two secondary minute teeth between the subapical tooth and two strong basal teeth (absent in M. enigmatica ). Generally the new species is a more typical member of the family than M. enigmatica , but the presence of 8 e-guard setae around papilla E (instead of 7 as a maximum number for Isotomidae , including M. enigmatica ) in labium makes M. fjellbergi sp. nov. also somewhat enigmatic. The adaptive importance of characters of the new species is not clear: a cylindrical dens with long lateral setae and lamellate mucro are usually associated with permanent contact with water, but this contradicts the normal shape of unguis and unguiculus and sharply differentiated seta covering. There is no doubt that the genus Mucronia should be treated as a member of Isotominae , but its similarity to the Tomoceridae family is striking. This similarity became even stronger taking into account the peculiarities of the new species lacking many features of M. enigmatica related to its life-style (dwelling on the water surface). As a result, M. fjellbergi sp. nov. appears to be rather similar to juveniles of Tomoceridae repeatedly described as new genera, viz. Architomocerura Denis or Paratomocerus Tarsia in Curia. These first instar juveniles of Tomoceridae formally resemble Mucronia in having no scales and only few or no setae on mucro ( Denis 1931; Tarsia in Curia 1938; Goto 1956). Despite these similarities, Mucronia remains a rather typical representative of Isotomidae . It may be speculated that the presence of ontogenetically early characters of Tomoceridae in adult Mucronia possibly reflects an ancient splitting of the latter from the Isotomidae evolutionary line, and that Tomoceridae and Isotomidae might have had a common ancestor with a lobed PAO which is lost in modern Tomoceridae . Two odd genera of Tomoceridae from South Hemisphere, Neophorella Womersley, 1934 ( South Africa) and Lasofinius Ireson et Greenslade, 1990 (Tasmania) , can be compared with Mucronia . These taxa have no scales on body and are characterized by tapering distally and weakly crenulated dens, fairly short mucro with two setae, and small simple PAO (only in Lasofinius ), the characters which are shared with the family Isotomidae . Annulated segments of antennae, spines ( Neophorella ) or barbed setae ( Lasofinius ) on dens, and the presence of abdominal bothriotrica (the latter has been proven only for Lasofinius ) made it possible to include the two genera to Tomoceridae ( Ireson and Greenslade, 1990) . All the characters mentioned above are not shown in Mucronia .
Etymology
Named after Arne Fjellberg who briefly characterized this species in his publication on cryophilic Isotomidae of the Northwestern Rocky Mountains ( Fjellberg 2010, page 46).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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