Paguristes timoni, Wallaard & Fraaije & Van Bakel & Nance & Lindholm & Jagt, 2023

Wallaard, Jonathan J. W., Fraaije, René H. B., Van Bakel, Barry W. M., Nance, John R., Lindholm, Adam & Jagt, John W. M., 2023, New hermit crab species (Anomura, Paguroidea) from the upper Miocene St Marys Formation of Maryland (USA), preserved in their host shells, Zootaxa 5227 (3), pp. 389-397 : 393-394

Paguristes timoni n. sp.

( Fig. 2 )

Zoobank: urn:lsid:zoobank.org:act:C4F34FA0-7A19-46B4-91BC-C93C621CD977

Diagnosis. Keeled merus with row of small teeth on distal margin; moveable finger corneous; fixed finger covered with rows of alveolate tubercles, decreasing in size on distal end. Upper margin with tubercles; cutting edge with several teeth proximally. Walking legs with keeled edge and row of tubercles.

Type material. The holotype, and sole specimen known to date, is CMM-I-4600.

Etymology. Named after the legendary misanthrope and hermit, Timon of Athens, who was popularized in the play ‘Timon of Athens’ by William Shakespeare (1564–1616).

Locality and stratigraphy. Driftwood Beach, Calvert County, Maryland, from the upper Miocene (Tortonian) Little Cove Point Member of the St. Marys Formation in a silty lens within Bed E ( Ward & Andrews 2008). Kidwell et al. (2015) identified this level as belonging to “SM-C,” assigned to Shattuck zones 22–23 and part of dinocyst zone 8.

Description. CMM-I-4600, preserved inside gastropod shell ( Busycon sp. ), length 25 mm, greatest width 17 mm. Manus missing from major (left) cheliped, carpus and merus preserved. Keeled merus with row of small teeth on distal margin. Minor (right) cheliped comprising complete propodus, lodged in gastropod aperture, measuring 7 mm length, 2 mm maximum width. Moveable finger corneous, fixed finger covered with rows of alveolate tubercles decreasing in size on distal end; most tubercles with alveoli, indicative of setal insertions; upper margin covered with tubercles; cutting edge with several teeth proximally; distal side not visible.

Carapace fragment preserved but covered; small portion visible lacking any specific details;

Single fragment of walking leg preserved showing keeled edge with row of tubercles. Several other fragments preserved, but unidentifiable due to weathering of specimen.

Remarks. In this novel form, the left cheliped is larger than the right one, which is diagnostic feature of diogenid and annuntidiogenid hermit crabs ( McLaughlin 2003; Fraaije 2014). The Maryland specimen is remarkably similar to the extant Paguristes candelae De Matos-Pita & Ramil, 2015 , from Mauritania (see below).

Discussion. Cheliped shape and ornament in P. timoni n. sp. compare closely with those of P. candelae , in that both have rows of tubercles and setae and tubercles decrease in size toward the distal end. The dorsomesial margin in P. candelae has three large tubercles; these are absent from P. timoni n. sp. The dorsal cheliped surface in the latter appears to be less convex in comparison with that of P. candelae , while the teeth along the cutting edge appear to be larger in the extinct form. The walking legs in both taxa show a keeled ridge with a row of spines, although the one in P. timoni n. sp. seems more acute.

Figures

FIGURE 2. Paguristes timoni n. sp., holotype, CMM-I-4600, from the upper Miocene St. Marys Formation in the cliff south of Little Cove Point, Calvert County (Maryland), in its host shell, and in ventral (A) and dorsal (B) aspects.