Aeger brevirostris Van Straelen, 1923

Jauvion, Clément, Charbonnier, Sylvain & Bernard, Sylvain, 2017, A new look at the shrimps (Crustacea, Decapoda, Penaeoidea) from the Middle Jurassic La Voulte-sur-Rhône Lagerstätte, Geodiversitas 39 (4), pp. 705-716 : 708-709

Aeger brevirostris Van Straelen, 1923

( Figs 1 ; 2 )

Aeger brevirostris Van Straelen, 1923: 87 , fig. 4; 1925: 91-93, fig. 54, pl. 2, fig. 4. — Roman 1928: 108, fig. 14. — Förster 1967: 164; 1980: 84. — Carriol & Riou 1991: 149-151, fig. 2, pl. 2, fig. 4, pl. 3, figs 1-4. — Fischer 2003: 241, figs 25, 26. — Charbonnier 2009: 15, 17, 18, 158, 219, 221-223, figs 240, 383-386, 388, tables 14, 24, 25. — Schweitzer et al. 2010: 8. — Charbonnier et al. 2010: 115, 121, 123-125, 129, figs 4a, 9b, 10a-d, tables 1-4. — Robin et al. 2015a: 465, fig. 1c, d; 2015b: 490, fig. 1b.

Antrimpos kiliani Van Straelen, 1923: 84 , 85 (partim), fig. 1; 1925: 67-70 (partim), pl. 1, figs 1, 2 (non fig. 3), pl. 2, fig. 2 (non fig. 1).

Aeger sp. – Van Straelen 1922: 982.

Archeosolenocera straeleni – Charbonnier et al. 2014: 375, 378, fig. 4d, table 1.

TYPE MATERIAL. — Lectotype UJF-ID.1754-1755 (coll. Gevrey, part and counterpart) designated by Van Straelen (1925) ( ICZN 1999: article 74.5); paralectotype UJF-ID.14031 (coll. Gevrey, figured by Van Straelen 1923: fig. 4).

TYPE LOCALITY. — Ravin des Mines, near La Boissine, La Voultesur-Rhône Lagerstätte, Ardèche, Rhône-Alpes, France.

TYPE AGE. — Early Callovian, Gracilis ammonite Zone. ADDITIONAL EXAMINED MATERIAL. — Aeger brevirostris : UJF- ID.1757, 11561, 14060, (coll. Gevrey), MNHN.F. A58216 , A58644, MNHN.F.R61852, R61853, R61854, R61855, R61856, R61857, R61858, R61859, R61860, R61862, R61863 (figured as Archeosolenocera straeleni by Charbonnier et al. 2014), R61865. — Antrimpos kiliani : lectotype UJF-ID.1790, paralectotypes UJF-ID.1789, 1792, 1924.

DESCRIPTION

Carapace

Subrectangular carapace (specimen MNHN.F.R61860, CL = 55 mm; CH = 29 mm) ; elongate, laterally flattened, dorsally smooth rostrum with one infrarostral spine medially; posterior margin dorsally concave with marginal ridge; anterior margin with deep antennal notch and shallow orbital one; straight dorsal margin; rimmed ventral margin; cervical groove steeply inclined, not joined to the dorsal margin, joined to short curved antennal groove; oblique and sinuous branchiocardiac groove, crossing all the carapace from the posterior margin to the hepatic region; very short inferior groove backward directed, not joined to ventral margin; almost straight hepatic groove joined anteriorly to cervical groove, and posteriorly to branchiocardiac groove; small hepatic spine near the junction between cervical and hepatic grooves; cephalic region with elongate postorbital spine.

Ornamentation of carapace

Smooth carapace.

Pleon

Subrectangular somites; s1 shorter than the others; s3 larger than the others; s1-s6 with smooth terga and pleura; rounded s1-s5 pleura; ventral margin of s1 pleuron with anterior process; s4 and s5 with posterior margin showing median articulation between s4-s5 and s5-s6 respectively; short and subquadrate s6; narrow, triangular telson with median longitudinal carina and acute distal extremity; telson shorter than uropods.

Cephalic appendages

Antennula (a1) with two long (c. carapace length) multiarticulated flagella; antenna (a2) with wider flagellum of undetermined length, long lamellar scaphocerite with dorsal longitudinal groove.

Thoracic appendages

Hypertrophied Mxp3 with rows of movable spines; branchlike Mxp3 dactylus; chelate P1-P3 with outer margins bearing a single row of spines; P2 longer than P1 and P3; achelate, smooth and slender P4-P5, shorter than P1-P3.

Pleonal appendages

Multi-articulated pleopods; uropods longer than telson with row of setae on distal margin; uropodal endopod shorter than uropodal exopod; uropodal endopod with longitudinal median carina flanked by longitudinal grooves; uropodal exopod with longitudinal median carina flanked by longitudinal grooves, the outer being deeper; uropodal exopod with crenel-shaped diaeresis showing one median pair of tubercles; outer margin of uropodal exopod confluent with diaeresis in strong distal spine.

DISCUSSION

Van Straelen (1923) described Antrimpos kiliani based upon an undetermined number of type specimens from the Gevrey collection. Actually, the original type material was composed of 24 specimens, and Van Straelen (1925) designated specimen UJF-ID.1790 as the lectotype ( Fig.1F ). Later, Carriol & Riou (1991) identified it as Aeger brevirostris and synonymized Antrimpos kiliani with Aeger brevirostris . Our examination of the lectotype reveals Mxp3 with rows of spines, P1-P3 outer margins bearing a single row of spines, and P2 longer than P1 and P3 ( Fig. 1F, G ). All these characters are diagnostic of Aeger brevirostris and leads us to confirm the proposed synonymy. Moreover, three paralectotypes (UJF-ID.1789, 1792, 1924) are also representatives of Aeger brevirostris .

Figures

FIG. 1. — Aeger brevirostris Van Straelen,1923 from the La Voulte Lagerstätte:A, B, specimen UJF-ID.1754-55 (lectotype;coll.Gevrey),right lateral view,part (A, UJF- ID.1755) and counterpart (B, UJF-ID.1754); C-E, specimen UJF-ID.14031 (paralectotype; coll. Gevrey), right dorsolateral view (C), detail (D) and line drawing (E); F, G, specimen UJF-ID.1790 (lectotype of Antrimpos kiliani Van Straelen, 1923; coll. Gevrey), right lateral view (F), line drawing (G). Abbreviations: ba, basipodite; ct, cephalothorax; di, diaeresis; en, uropodal endopod; ex, uropodal exopod; Mxp3, third maxilliped; P1-P5, pereiopods 1 to 5; s1-s6, pleonal somites 1 to 6; sk, endophragmal skeleton; sp, spine; t, telson; tb, tubercles. Photographs: A-C, F, L. Cazes; D, N. Podevigne. Line drawings: C. Jauvion. Scale bars: 20 mm.

FIG. 2. — Aeger brevirostris Van Straelen, 1923 from the La Voulte Lagerstätte: A-D, specimen MNHN.F.R61863, left lateral view (A), right lateral view (B), ventral view (C), line drawing (D); E, F, specimen FSL 170532,right lateral view (E), line drawing (F); G-I, specimen MNHN.F.R61852, right lateral view (G), details (H-I). Abbreviations: a, branchiocardiac groove;α, hepatic spine;b1, hepaticgroove;ct, cephalothorax;e1e, cervical groove;en, uropodal endopod;ex, uropodalexopod;i, inferior groove;mov sp, movable spines;Mxp3, third maxilliped;P1-P5, pereiopods 1 to 5;pl, pleon;po, postorbital spine;r, rostrum;s1-s6, pleonalsomites 1 to 6;sc, scaphocerite;set, setae; t, telson.Photographs:A, C-E, N.Podevigne;H, I, C.Jauvion;G, P.Massicard (e-recolnat Project,MNHN).Line drawings:C.Jauvion.Scale bars:A-G,10 mm;H,I, 2 mm.