Electrolana madelineae, Schädel & Hyžný & Haug, 2021

Schädel, Mario, Hyžný, Matúš & Haug, Joachim T., 2021, Ontogenetic development captured in amber - the first record of aquatic representatives of Isopoda in Cretaceous amber from Myanmar, Nauplius (e 2021003) 29, pp. 1-29 : 21-23

Electrolana madelineae sp. nov.

Figs. 2–6 , 7A , 8A , 9 , 10A, S 1 , S 6–8

Zoobank: urn:lsid:zoobank.org:act:8D1A3CC8-B700-4819-85A9-4ACBA02966D0

Etymology. After Madeline Pankowski of Rockville, Maryland, USA, daughter of Mark Pankowski who donated the types to the Museum of Natural History in Vienna.

Material examined. Holotype: NHMW 2017/0052/0001 , Natural History Museum Vienna . Paratype: NHMW 2017/0052/0002 , Natural History Museum Vienna .

Ontogenetic stage of the type. The paratype is of a manca stage; the holotype is a post-manca juvenile or an adult.

Type locality. Near Noje Bum, Hukawng Valley, Kachin State, Myanmar.

Type stratum. Unknown stratum, 98.8 million years, earliest Cenomanian, earliest Late Cretaceous, after Shi et al. (2012).

Differential diagnosis. Body drop shaped in dorsal view, tapering posteriorly, about 2.5 to 2.2 times longer than wide; tergite of trunk segment 1 about twice as long as succeeding segments; dactylus and claws of trunk appendages 1–3 gently curved inwards, not hook-like; coxal plates well developed, triangular in trunk segments 4–7 (postocular segments 10– 13); basipod of trunk appendage 6 broad, posterior margin convex, median ridge along the mid-line of the lateral surface; coxal plate of trunk segment 7 (postocular segment 13) very conspicuous in dorsal view, extending distally to the level of pleon segment 5; tergites of pleon segments 1–5 (postocular segments 14–18) free; tergite of pleon segment 1 (postocular segment 14) short, laterally covered by the tergite of trunk segment 7 (postocular segment 13); basipod of pleopod 1 (postocular segment 14) wider than long; pleopod 1 not operculate, concealing the succeeding pleopods; tergite of pleon segment 5 (postocular segment 18) with free lateral margins, not covered by the tergite of the preceding segment; endopod of pleopod 5 (postocular segment 18) more slender than the corresponding exopod, no setae on the distal margin; pleotelson half-oval in shape, slightly longer than wide, straight anterior margin, without distinct ornamentation on the dorsal surface, posterior margin without large spines, posterior margin with numerous setae grouped in the posterior-most part; uropod endopod about twice as long as wide, with median angle, not ’truncated’.

Remarks on the differential diagnosis. Due to the limited set of characters available, using the current methods, this diagnosis will not be able to differentiate the new species from all fossil or extant species. Thus, this differential diagnosis should be seen as a short recap of the description with respect to the discussion above.

Systematic interpretation. Cymothoida incertae sedis, nec Anuropus, nec Tridentella , nec Corallanidae , nec Aegidae , nec Cymothoidae , nec Epicaridea, nec Gnathiidae , nec Protognathia, nec Urda, nec Bathynomus , nec Colopisthus , nec Boorlana, nec Parabathynomus, nec Bahalana, nec Arubolana, nec Cirolanides, nec Typhlocirolana, nec Turcolana, nec Speocirolana, nec Sphaeromides, nec Skotobaena , nec Sphaerolana, nec Atarbolana , nec Aphantolana, nec Annina , nec Pseudaega , nec Politolana , nec Oncilorpheus, nec Natatolana , nec Haptolana, nec Excirolana, nec Eurydice , nec Conilera , nec Dolicholana . The following extant ingroups of Cymothoida represent likely affinities for Electrolana madelineae sp. nov.: Aatolana, Pseudolana, Plakolana, Odysseylana, Neocirolana, Eurylana, Baharilana , and Cirolana .

Remarks on the systematic interpretation. The Latin term nec (= but not) is used to list ingroups of Cymothoida, to which Electrolana madelineae sp. nov. does not belong (as applied in Schädel et al., 2019a).

Figures

Figure 1. A: Map of Myanmar, white star marks the location of the Burmese amber mining sites near the town Noje Bum, base map from OpenStreetMap (openstreetmap.org); B: palaeogeographic world map, Aitov projection, 100 million years in the past, base image from PALEOMAP project (Scotese, 2016), red star marks the location of the Burmese amber sites.

Figure 2. Paratype of Electrolana madelineae sp.nov.(NHMW 2017/0052/0002).A: Habitus indorsal view,white lightmicroscopy, coaxial light and polarising filter, 300x (VHX); B: habitus in dorsal view, red-cyan stereo anaglyph, white light microscopy, 200x (VHX); C: head region in antero-dorsal view, white light microscopy, 200x (VHX); D: head region in antero-dorsal view, red-cyan stereo anaglyph,white light microscopy,200x (VHX).a, antenna; al, antennula; ce, compound eye; cp6, coxal plate of trunk segment 6; p3–6, trunk appendages 3–6; pl, pleon segments 1–5; plp5, pleopod 5; pr1–7, trunk segments 1–7; pt, pleotelson; u, uropod.

Figure 3.Paratypeof Electrolana madelineae sp.nov.(NHMW 2017/0052/0002).A:Habitus inventralview,white lightmicroscopy,300x (VHX); B: habitus in ventralview,red-cyan stereo anaglyph, white light microscopy,200x;C: habitus in ventralview,epifluorescence microscopy, 4x (BZ); D: distal region of trunk appendages 1 and 2 in ventral view, right body side, white light microscopy, 300x (VHX); E: head in ventral view, white light microscopy, desaturated with colour markings, red mandible, blue maxillula, yellow maxilla, green maxilliped, 300x (VHX); F: pleon region in ventral view, white light microscopy, 300x (VHX); G: pleon region in ventral view, white light microscopy, desaturated and inverted, with color markings, yellow basipod, green endopod, blue exopod, 300x (VHX). a, antenna; al, antennula; cl, clypeus; dc, dorsal claw; ed, endite of the maxilliped; fl, frontal lamina; lb, labrum; mp, mandibular palp; mxp, maxilliped; p1–6, trunk appendages 1–6; plp1–5, pleopod1–5; pt, pleotelson; sr, serrationpattern; u, uropod.

Figure 4.Holotype of Electrolana madelineae sp.nov.(NHMW 2017/0052/0001).A: Habitus indorsal view, white lightmicroscopy, 200x (VHX). B: anterior head region in ventro-lateral view, transmitted light microscopy, 4x (BZ); C: anterior body region in ventro-lateralview,white light microscopy,200x(VHX);D: anterior trunk region inventro-lateral view,white lightmicroscopy,150x (VHX); E: head region in dorsal view, left body side, white light microscopy, 200x (VHX). a, antenna; al, antennula; ce, compound eye; cp6–7, coxal plate of trunk segment 6–7;mp, mandibular palp; o, seed shrimp (Ostracoda); p1–7, trunk appendages 1–7; pt, pleotelson; ub, uropod basipod; un, uropod endopod; ux, uropod exopod.

Figure 5: Holotype of Electrolana madelineae sp.nov. (NHMW 2017/0052/0001), volume rendering images based on micro-CT data.A:Habitus in dorsal view,orthographic projection;B:habitus in ventral view,orthographic projection;C:habitus in ventral view, red-cyan stereo anaglyph, perspective projection; D: habitus in lateral view, right body side, red-cyan stereo anaglyph, perspective projection. a, antenna; al, antennula; cp7, coxal plate of trunk segment 7; p1–6, trunk appendages 1–6; pt, pleotelson; un, uropod endopod; ux, uropod exopod;?, unknown material forming an irregular bubble.

Figure 6. Drawing of the holotype of Electrolana madelineae sp. nov. (NHMW 2017/0052/0001), dorsal view, composite of microscopic images and micro-CT scan data.

Figure 7. Comparisonof the uropodmorphology between Electrolana madelineae sp.nov.and an extant representative of Oniscidea. A: Holotype of Electrolana madelineae sp. nov. (NHMW 2017/0052/0001), pleon region in latero-dorsal view, epifluorescence microscopy, 4x (BZ); B: Philoscia cf.muscorum (Scopoli, 1763), posterior pleon region in dorsal view, white light microscopy, 200x (VHX).pl, pleon segments 1–5;pr7, trunk segment 7;pt, pleotelson; ub,uropod basipod; un, uropod endopod; ux,uropod exopod.

Figure 8. Comparison of the distal part of trunk appendage 1 in different lineages of Cymothoida. A: Electrolana madelineae n. sp., schematic reconstruction;B: Cirolana australiense Hale, 1925, redrawn from Bruce (1986, fig.114L); C: Elthusa vulgaris (Stimpson, 1857), drawn after van der Wal and Haug (2020, fig. 16B). d, dactylus, dc, claws of dactylus, pp, propodus.

Figure 9. Holotype of Electrolana madelineae sp. nov. (NHMW 2017/0052/0001), habitus in ventrolateral view and surrounding objects in the resin, volume rendering image, two different transfer functions and clipping planes applied, orange colour transfer function solely depicts extremely low-x-ray contrast areas (gas phase). ab, air bubble; l, leg, Euarthropoda.

Figure 10. Graphical summary of all known manca-stage or larval fossils of Isopoda, reconstruction line drawings, free pleon tergites (postocular segments 14–18) in darker grey. A. Paratype of Electrolana madelineae sp. nov. (NHMW 2017/0052/0002); B: Aquitanoscia chiapasensis Broly et al., 2017; C: Vacuotheca dupeorum Schädel et al., 2019b; D: IHNFG-4951-Ep1 (‘specimen 2’) Serrano Sanchez et al.(2016); E: openstreetmap.org IHNFG-4964-Ep2 (‘specimen 5b’) Serrano Sanchez etal.(2016); F: IHNFG- 5321-Ep1 (‘specimen 6’) Serrano Sanchez et al. (2016); G: IHNFG-4971-Ep1 (‘specimen 3’) Serrano Sanchez et al. (2016); H: IHNFG-4939-Ep1 (‘specimen 1’) Serrano Sanchez et al. (2016).