Pseudactium credoi Owens and Carlton, 2017

Owens, Brittany E. & Carlton, Christopher E., 2017, A New Species of Pseudactium Casey (Coleoptera: Staphylinidae: Pselaphinae) From Tennessee, USA, The Coleopterists Bulletin 71 (3), pp. 468-470 : 469-470

Pseudactium credoi Owens and Carlton , new species

( Figs. 1–2 )

Type Material. Holotype: (male) TENN ., Wilson Co. Lane Farm Glade 36 °01’ 52 ”N 86°22’12”W 12 June 1997 T.L.Schiefer / blacklight in Cedar Glades / William H. Cross Expedition. (FMNH). Paratypes: (2 males) TENN., Wilson Co. Lane Farm Glade 36°01’52”N 86°22’12”W 12 June 1997 T.L.Schiefer / blacklight in Cedar Glades / William H. Cross Expedition. (FMNH, MEM).

Etymology. This species is named after Dr. Keith Credo, a business professor at the University of Louisiana at Lafayette and best friend of the first author, whose personal and professional support has been invaluable.

Diagnosis. Pseudactium credoi is most similar to Pseudactium parabolicum (Brendel) and P. ursum in the form of the ventral projections of ventrite III extending beyond the lateral margins of the ventrite ( Fig. 2 ). Pseudactium credoi differs from the other two species in the presence of a metacoxal spine and the absence of any other modifications to the meso- or metathoracic legs. The form of the aedeagus is also unique, with the broad sinuate median lobe and the accessory process modified into a series of flattened projections ( Fig. 1 ).

Description. MALE holotype. Measurements: HL = 0.17 mm, HW = 0.29 mm; PL = 0.30 mm, PW = 0.30 mm; EL 0.40 mm, EW 0.48 mm; A1–6, respectively, = 0.04, 0.07, 0.13, 0.09, 0.15, 0.03 mm; An1–11, respectively, = 0.04, 0.04, 0.02, 0.02, 0.02, 0.02, 0.02, 0.02, 0.03, 0.03, 0.07 mm; MP1–4, respectively, = 0.01, 0.02, 0.01, 0.02 mm; GL = 0.41 mm, GW = 0.25 mm; ML = 2.2 mm. Integument: Head, pronotum, elytra, and abdomen light brown, appendages yellow. Entire surface covered with sparse, semierect pubescence. Pubescence in gular area capitate. Thorax: Procoxa unmodified, protibia with minute preapical spine, setae denser towards apex, 2 nd protarsomere not swollen. Mesocoxae contiguous, unmodified, mesotrochanter weakly concave along ventral margin, truncate apically, mesotibia unmodified, setae slightly denser towards apex. Metacoxa with spine, metatibia unmodified, setae slightly denser towards apex. Abdomen: Third ventrite with pair of triangular, apically setose lateral lobes extending beyond lateral margins (visible in dorsal view). Genitalia: Aedeagus asymmetrical. Elongate process of aedeagus broad, slightly sinuate. Accessory process fused with elongate process near base, modified into a series of flattened projections.

Distribution. Pseudactium credoi is only known from the type locality in Wilson Co., TN.

Comments. When using the dichotomous key to species of Pseudactium provided by Carlton and Chandler (1994), this species will run to couplet 9. Modifications to those made to couplet 8 (Carlton 1995) integrate P. ursum into this key. To distinguish P. credoi from P. ursum, further modifications to the remainder of the key are as follows:

8. Lateral processes of ventrite III larger, at least in ½ length of ventrite III not extending beyond lateral margin, not visible in dorsal view .............................................. 9

8 ′. Lateral processes of ventrite III larger, at least ½ length of ventrite III, extending beyond lateral margin, clearly visible in dorsal view, accessory process of aedeagus extremely slender and smooth ........ Pseudactium ursum

8 ′′. Lateral process of ventrite III larger, at least ½ length of ventrite III ( Fig. 2 ) extending beyond lateral margin, clearly visible in dorsal view, accessory process of aedeagus modified into a series of flattened projections ( Fig. 1 ). .. .. ... .. ... .. ... Pseudactium credoi

8 ′′′. Lateral processes of ventrite III smaller, consisting of low, setose timidities near postlateral angle of ventrite III ..............................10

Figures

Figs. 1–2. Pseudactium credoi. 1) Aedeagus, dorsal view; 2) Ventrite III lateral process, left half.