Glypturus sikesi, Klompmaker & Hy̆z & & Kowalew, 2016

Klompmaker, A., Hy ̆ z, Matu ̆ s, , Roger W. Port & Kowalew, nd Michał, 2016, Growth, inter- and intraspecific variation, palaeobiogeography, taphonomy and systematics of the Cenozoic ghost shrimp Glypturus, Journal of Systematic Palaeontology 14 (2), pp. 99-126 : 112-114

Glypturus sikesi sp. nov.

( Fig. 14)

Diagnosis. Lateral tuberculation on outer propodal side from base of fixed finger diagonally to lower margin and proximal lower corner. Lateral tuberculation on inner propodal side covering large lower part of manus in medium to large specimens with lower margin of tuberculated area diagonally crossing from area of articulation of dactylus toward (but not reaching) proximal lower corner, tuberculation in small specimens more variable but mostly as in larger specimens. Occlusal margin dactylus without teeth or exhibiting two weak to medium teeth. Outer side carpus without tubercles; inner side with tubercles on lower ~75%.

Derivation of name. Named after the owner (Mr Lamar Sikes) of the Sikes Sand Mine in Florida, from which all currently known specimens originated.

Material. Holotype: UF 235152 ( Fig. 14H — J) ; Paratypes: UF 235355 ( Fig. 14A — D), 235154 ( Fig. 14E — G), 235370 ( Fig. 14K — M), 235401 ( Fig. 14N — Q), 235166 ( Fig. 14T, U), 248029 ( Fig. 14X — Z), 248038 ( Fig. 14 Al — Cl), 248041 ( Fig. 14 Dl, El) and 248042 ( Fig. 14 Gl, Hl).

Other material (P = propodus; D = dactylus; C = carpus; M = merus; FF = fixed finger): UF 248044 ( Fig. 14R, S), 235420 ( Fig. 14V, W), 248028 ( Fig. 14 Fl), 232621 (1D), 232622 — 232632 (1P each), 232633 (14P), 232660 (1P), 232661 (8P), 232662 (2P), 235153 (1P), 235155 — 235164 (1P each), 235165 (1D), 235167 — 235168 (10P), 235169 (7P), 235356 — 235369 (1P each), 235371 (3P), 235372 — 235373 (15P each), 235374 (10P), 235399 — 235400 (1P each), 235402 — 235403 (1D each), 235404 (1FF), 235405 — 235419 (1P each), 235421 — 235432 (1P each), 235433 (33P), 248034 (1P), 248037 (1P), 248039 (1M), 248040 (4C), 248043 (10D), 248045 — 248049 (1P each), 251651 (1P), 251652 (1C), 251653 — 251658 (1P each) and 251901 (1C).

Occurrence. All specimens were collected at Sikes Sand Mine 02 (type locality) in Washington County , Florida, USA, and come from the upper Miocene Choctawhatchee Formation (see Geological setting).

Description. Manus up to ~ 23 mm long and ~ 19 mm tall, length/height ratio ~1.0 — 1.3. Upper margin curving inward distally, proximally keeled, typically bearing three prominent spines pointing distally, proximalmost spine around mid-margin, keel terminating in blunt corner proximally. Lower margin sharp and keeled, lined with a row of setal pits on inner lateral side. Proximal margin convex on outer face, concave on inner; heightwise groove near proximal margin concave on inner side, concave to straight on outer side. Distal margin with protrusion just above fixed finger, hinge point with dactylus expressed as notch. Lateral tuberculation on outer side from base of fixed finger diagonally to lower margin and proximal lower corner. Lateral tuberculation on inner side covering large lower part of manus in medium to large specimens with lower margin of tuberculated area diagonally crossing from area of articulation of dactylus toward (but not reaching) proximal lower corner, tuberculation in small specimens less prominent, largest specimens contain additional tubercles on lower margin below two distalmost spines on upper margin. Fixed finger curving inward, triangular, sharply pointed, with distinct blunt tooth on occlusal margin around mid-length, tooth pointing distally. Occlusal margin dactylus without teeth or exhibiting two weak to medium teeth with proximalmost one being largest; tip dactylus hooked, curving downward. Carpus subrectangular with rounded distalmost lower corner on outer side, slightly taller than wide; upper margin keeled and smooth with setal pits on inner part margin; lower margin keeled, exhibits spines on inner side; distal margin straight to slightly concave; proximal margin concave on inner side, convex on outer side with one tooth approximately one-third the distance from upper margin directed proximally; distalmost lower corner with one spine directed distally; outer side without tubercles; inner side with tubercles on lower ~75%. Outer side merus with longitudinal keel in centre; tuberculated below keel, especially proximally; spinose and convex lower margin; upper margin exhibiting three distally directed spines. Inner side merus flattened with tubercles on lower half and proximally. Other parts of species not preserved.

Remarks. Intraspecific variation is observed in the strength of the teeth on the dactylus ( Fig. 14R — U, Dl, El) and the tooth on the fixed finger. Furthermore, the number of spines on the upper margin of the propodus is typically three, but some (<10%) specimens exhibit more (four: UF 235424; five: UF 248034) or fewer spines (one: UF 248037; two: UF 232625, UF 235408). Size-related variation is particularly expressed in the tuberculation pattern on the inner side of small specimens as tubercle coverage is more variable in these specimens, an increasing length/height ratio with size, and an increasing coverage of tubercles on the inner side with size. A nearly equal number of major propodi (defined here: length manus ± 15 mm) is left-handed (34) and right-handed (36) (x 2 = 0.06; p = 0.81).

The differences between Glypturus sikesi sp. nov. and G. acanthochirus , G. armatus , G. berryi , G. fraasi , G. laurae , G. persicus , G. munieri and G. pugnax are the same as described for G. panamacanalensis sp. nov. since the tubercular patterns of G. sikesi sp. nov. and G. panamacanalensis sp. nov. are nearly identical on the propodus. Glypturus spinosus bears much stronger spines on the upper margin compared to the new species. Tubercular patterns are more difficult to use to distinguish G. toulai and G. panamacanalensis sp. nov. from the new species, but sufficient differences were found to justify erection of G. sikesi sp. nov. (see above).