Tshudy et al.—New Oligocene lobster from Hungary
prominence ω, antennal groove becomes very faint, bifurcates. Upper branch extends a short distance in direction of base of rostrum. Lower branch extends toward anterior margin, effacing before reaching latter. Antennal spine not preserved. Antennal and postantennal
region smooth, uninflated. Gastro-orbital and buccal grooves absent.
Postantennal spine absent. Hepatic spine absent. Cervical
and postcervical spines/spinules absent. Postorbital spine strong at base, angles antero-dorsally. Supraorbital spine region not preserved, but seems to be followed by a nodose, supraorbital carina. Cuticle of cephalothorax smooth (not granulate), except
ventrally, below level of prominence χ, where with low, rounded granules. Pleon represented by segments one–five (both left and right
sides of lobster specimen). All tergites appear to be without sculpture (i.e., lacking grooves, etc.) and with smooth cuticle lacking any surface ornamentation. Tergum-pleuron boundaries unmarked by any ridge, terrace, or other demarcation. Pleuron one (left side) a parallelogram angling anteroven-
trally. Pleuron two (left side) subquadrate; anterior margin convex, posterior margin convex at top then concave for remainder. Anteroventral corner rounded; posteroventral corner pointed posteroventrally. Pleura three–five cordate, terminating in sharp, posteroventrally directed point. Pleuron two with broad, submarginal furrow bordering, but well inside, anterior and posterior margins. Pleura three and four with similar furrow bordering upper part of posterior margin. Each pleuron surface
173
terminations occlude. Cuticle on fingers minutely, densely pitted, especially adjacent to dentition. Denticles of left cheliped conical, slightly longer than wide,
densely arranged, of varying sizes. Smallest ~0.15mmdiameter at base and about twice as long. Larger denticles ~0.3mm wide at base, ~0.5mm long. A very few much larger denticles; largest, located proximal of mid-length on pollex, is triangular, ~2mm wide at base and equally long. Denticles mostly perpendicular to fingers. Largest denticle is distally directed.
Etymology.—The species name derives from the collecting locality in Hungary.
Remarks.—The new species is referred to Homarus, but with acknowledgement of similarities to the extinct Hoploparia. The new species has: (1) a generally smooth (not granulose) cepha- lothorax, pleon, and chelipeds; (2) smooth antennal and post- antennal regions; (3) only indistinct ventral extension of the branchiocardiac groove; and (4) unsculptured pleonal tergites. Nothing on the cephalothorax or pleon is inconsistent with Homarus, but the fossil specimen’s cutter claw is elongate and Hoploparia-like, thus complicating the generic placement. Below we compare the late Oligocene (ca. 30 Ma)
broadly, slightly inflated medially and along margin. Pleuron five gently convex overall. Pleura four and five (right side of lobster) with a few low, rounded nodes. Pleura two–five with a large pore near termination. At least the anteroventral margin of pleura three, four, and five with a very fine, rounded, bead for margin; shown best on pleuron five as viewed on right side of lobster, although pleura three, four, and five of left side also show this bead (a similar bead is seen on the anterior, but not posterior, sides of the pleura of Homarus americanus). On pleuron five, bead breaks into minute serrations near pleuron termination. Telson not preserved. Specimen preserved with portions of right (crusher) and left
(cutter) claws. Right cheliped rotated inward so that merus, carpus, and propodus lower (ventral) surface and propodus outer margin are
exposed.Merus lower surface gently convex overall; cuticle smooth. Merus with strong spine at inner proximal and inner distal corners. Merus outer surface with granules. Carpus lower surface rather flat overall, with strong spine at inner and outer distal corner; cuticle smooth, but with large, transversely elongate pits. Propodus incomplete at approximately mid-length. Manus ovate in cross section. Manus outer margin narrowly squared-off proximally, becoming sharply rounded for most of length. Cuticle of lower surface smooth. Left (cutter) claw lower surface exposed. Claw elongate,
approximately 5x longer than wide (~74mmlong and estimated 15mm wide). Propodus outer margin sharply rounded. Pollex subovate in crosssection, ~40mm long, 8.4mm at widest; thus 0.21x as wide as long. Dactylus ~30mm long; dactylus subrectangular in cross section. Fingers rather straight, parallel but curving toward each other near terminations. Unsure if
specimen to all species of Homarus known from the Eocene epoch (56.0–33.9 Myr) to the Recent. Given the long history of taxonomic confusion surrounding Homarus and Hoploparia, we also compare (further below) the new species to all known Eocene–Recent species of Hoploparia. No existing species of either genus has a morphology matching that of the new Hungarian fossil. Comparison to Oligocene (33.9–23.03 Myr) species.—
Homarus klebsi is known from the lower and upper Oligocene of northern Germany (and, according to specimen labels at the Institut royal des Sciences naturelles de Belgique at Brussels, from the Oligocene [‘Tongrien’] of formerly Palmnicken, eastern Prussia [now Kaliningrad, Russian Federation]). Homarus klebsi differs from the new species by: (1) its gigantic size, and in having (2) a distinct ventral extension of the bran- chiocardiac groove and (3) a suprahepatic groove (Noetling, 1885, pl. 7, fig. 1 [same figure in Freess, 1992, pl. 4B]). Homarus lehmanni Haas, 1889 has been described from
the lower Oligocene (Rupelian) of Germany. This species is known only by a fragmentary carpus and fragmentary merus and, therefore, is hardly comparable to the new material. Van Straelen (1936) and Verheyden (2002) considered H. lehmanni to be a synonym of H. percyi Van Beneden, 1872. Homarus percyi is known from the lower Oligocene
(Rupelian) of northwest Belgium, Germany, and Russia. The claws of H. percyi are gigantic, and more robust in proportions than those of the new species; they also have spikes on the propodus upper and lower surface. Comparison to Eocene (56–33.9 Myr) species.—Homarus
klebsi (as above). Homarus morrisi Quayle, 1987 from the Eocene of southern England was isolated from Hoploparia gammaroides M’Coy, 1849. It differs from the new species in being conspicuously pitted, in having a more granulose promi- nence ω, a slightly different carapace groove configuration, and a more strongly pitted pleon surface.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175 |
Page 176 |
Page 177 |
Page 178 |
Page 179 |
Page 180 |
Page 181 |
Page 182 |
Page 183 |
Page 184 |
Page 185 |
Page 186 |
Page 187 |
Page 188 |
Page 189 |
Page 190 |
Page 191 |
Page 192 |
Page 193 |
Page 194 |
Page 195 |
Page 196 |
Page 197 |
Page 198 |
Page 199 |
Page 200 |
Page 201 |
Page 202 |
Page 203 |
Page 204
