Pustulina minuta ( Schlotheim, 1822 )

Devillez, Julien & Charbonnier, Sylvain, 2021, Review of the Late Jurassic erymoid lobsters (Crustacea: Decapoda), Geodiversitas 43 (2), pp. 25-73 : 55-56

Pustulina minuta ( Schlotheim, 1822)

( Fig. 15 )

Macrourites minutus Schlotheim, 1822: 28 , pl. 3, fig. 3. Glyphea verrucosa Münster, 1839: 21 , pl. 9, fig. 11 (non 12). — Fraas 1855: 94.

Astacus minutus – Germar 1827: 102.

Glyphea minuta – Münster 1839: 20, pl. 9, figs 8-10.

Eryma minuta – Bronn 1849: 579. — Oppel 1861: 356; 1862: 39, pl. 8, figs 6-8. — Beurlen 1928: 164. — Vialle 1948: 61. — Secrétan 1964: 68.

Enoploclytia minuta – Van Straelen 1925: 284. — Glaessner 1929: 154 (pars.).

Enoploclytia fuciformis – Van Straelen 1925: 285 (pars.). — Glaessner 1929: 156 (pars.).

Phlyctisoma minuta – Förster 1965: 140; 1966: 142, pl. 18, fig. 9. — Frickhinger 1994: 126, fig. 224.

Pustulina minuta – Feldmann & Titus 2006: 64. — Garassino & Schweigert 2006: 11, 36, fig. 8, pl. 2, fig. 1, pl. 11, fig. 6, pl. 12, figs 1-2. — Schweitzer et al. 2010: 26. — Charbonnier & Garassino 2012: 864, 865, fig. 3E. — Schweigert 2015: fig. 545. — Odin et al. 2019: 654 , fig. 7D, ap. 1.

Eryma verrucosa – Oppel 1861: 359; 1862: 38, pl. 8, fig. 5. — Feldmann & Titus 2006: 64. — Schweitzer et al. 2010: 26.

TYPE MATERIAL. — Holotype MFN 2236 P1383/5 MB.A.0254 . TYPE LOCALITY. — Eichstätt , Bavaria, Germany. TYPE AGE. — Tithonian .

DESCRIPTION

Carapace

Sub-cylindrical carapace; short, spiny rostrum; fusiform intercalated plate; orbital notch slightly curved; deep cervical groove, almost straight and sub-vertical, joined to dorsal margin and to antennal groove; deep antennal groove; elongated gastro-orbital groove, joined to cervical groove at carapace mid-height, with two divergent branches delimiting two gastro-orbital lobes; deep postcervical groove, inflected at carapace mid-height, inclined dorsally, not joined to dorsal margin; shallow branchiocardiac groove, not joined to dorsal margin and interrupted in branchial region; narrow and shallow cardiac groove, straight, strongly inclined forward, joined to the postcervical groove and to dorsal margin.

Pleon and uropods

Somites with wide subtriangular pleurites, becoming shorter from s4 to s6, with a slightly rounded posterior margin, with a strongly inflated and rounded bulge on their basis; telson with a median groove and two longitudinal crests; uropods as long as telson; uropodal endopods with a longitudinal carina; uropodal exopods with a diaeresis.

Cephalic appendages

Last segment of antennular peduncles (basipodite) articulated with two flagella, flagella made of numerous and short cylindrical articles; antennas made of numerous and short cylindrical articles; short, triangular scaphocerite.

Thoracic appendages

Elongated Mxp3, with two cylindrical distal segments lacking of spines; chelate P1; P1 propodus short, as long as wide; narrow, slightly inflated dactylar bulge; short, wide P1 fingers, straight dorsally, slightly curved downward, equal in length; occlusal margin without teeth; P1 carpus short, subtriangular; elongated P1 merus; P2-P3 chelate.

Ornamentation

Carapace densely covered by rounded tubercles, smaller and closer in branchial region; intercalated plate covered by tubercles; tergites and pleurites of pleonal somites covered by small depressions; longitudinal crest of the telson bearing a row of tubercles; telson covered by thin tubercles and with two small spines on its external margin; uropodal endopods covered by thin tubercles; P1 propodus densely covered by coarse tubercles; P1 fingers with irregular carina and rounded depressions; P1 carpus densely covered by coarse tubercles; P1 merus with coarse tubercles in its distal part; smooth P2-P3 and P5; P4 propodus with posterior spines.

DISCUSSION

The assignation to Pustulina is based on the typical groove pattern: the wide and long gastro-orbital groove with two divergent branches, the inflected postcervical groove, joined to the posterior extremity of the hepatic groove, the concave hepatic groove, and the presence of a cardiac groove.

After the original description by Schlotheim (1822), Münster (1839) described Glyphea verrucosa based on an isolated P1 chela from the same locality. Later, Glaessner (1929), followed by Förster (1966) and Garassino & Schweigert (2006), established the synonymy between M. minutus and G. verrucosa , while Schweitzer et al. (2010) reported Eryma verrucosa as Incertae sedis in Erymidae section. The lectotype of G. verrucosa is a true chelae, so it cannot be maintained within Glyphea Meyer, 1835 , because glypheid lobsters have subchelate P1-P3. Moreover, comparisons with the specimens of Pustulina minuta show strong similarities in both forms: rectangular propodus with short and wide fingers typical of Pustulina ; a propodus densely and irregularly covered by coarse rounded tubercles and fingers with depressions and irregular carina. These similarities support the synonymy between P. minuta and G. verrucosa previously established by Glaessner (1929).

The compression of the specimens of Pustulina minuta makes difficult comparisons with other species. The cervical groove is almost straight while that of P. calloviensis , P. colossea , and P. elegans is clearly curved or sinuous. Moreover, contrary to P. colossea , P. occitana , P. spinulata , P. suevica , and P. tuberculata , there is no well-marked antennal row in P. minuta . There is also no row in the gastric region contrary to P. trisulcata and no depressions contrary to P. calloviensis and P. elegans . Finally, the P1 fingers of P. minuta do not have a terminal hook contrary to P. cretacea and some specimens of P. suevica .

Figures

FIG. 15. — Pustulina minuta (Schlotheim, 1857) from the Tithonian of Germany and Pustulina sp.: A, holotype MFN 2236 P1383/5 MB.A.0254 of P. minuta from Eichstätt; B, lectotype BSPG AS VII 182 of Glyphea verrucosa Münster, 1839 from Eichstätt; C, D, specimen MFN 2236 P1383/5 MB.A.1119 of P. minuta from Solnhofen: general view (C), schema of the carapace (D); E, specimen 2236 P1383/5 MB.A.2863 of P. minuta from Solnhofen; F, specimen BSPG AS VIII 78 of P. minuta from Solnhofen; G, specimen BSPG 1952 XV 570 of P. sp. (Kimmeridgian, Nagelsberg near Heubach, Germany). Abbreviations: a, branchiocardiac groove; b, antennal groove; b1, hepatic groove; c, postcervical groove; cd, cardiac groove; d, gastro-orbital groove;e1e, cervical groove; i, inferior groove;ip, intercalated plate. Photographs and line drawing: J. Devillez. Scale bars: 1 cm.