Crucisternum vanessae, Girón & Short, 2018

Giron, Jennifer C. & Short, Andrew Edward Z., 2018, Three new genera of acidocerine water scavenger beetles from tropical South America (Coleoptera, Hydrophilidae, Acidocerinae), ZooKeys 768, pp. 113-158 : 122-124

Crucisternum vanessae sp. n. Figs 2E-H ; 6D ; 7 ; 8D

Type material examined.

Holotype (male): " SURINAME: Sipaliwini district/ 3°53.942'N, 56°10.849'W, 733 m/ CSNR: Tafelberg Summit, near/ Caiman Creek Camp, margins & leaf packs in Caiman Creek/ leg. Short & Bloom; 19.viii.2013/ SR13-0819-05D" (NZCS). Paratypes (188): SURINAME: Sipaliwini district: " 3°55.600'N, 56°11.300'W, 600 m/ CSNR: Tafelberg Summit/ Augustus Creek, seepage on/ wall; leg. Short & Bloom/ 14.viii.2013; SR13-0814-01B" (3, SEMC); " 3°56.351'N, 56°10.954'W, 614 m/ CSNR: Tafelberg Summit/ Geijskes Creek, margin of creek/ w/ detritus; leg. Short & Bloom/ 15.viii.2013; SR13-0815-02A" (24, NZCS, SEMC); same, except "seep on wall/ 16.viii.2013; SR13-0816-01A" (1, SEMC); same, except "leaf packs & wood jams/ SR13-0816-01B" (4, SEMC); same, except "leaf packs & rock scrubbing; leg. D. Bloom/ SR13-0816-01D" (13, SEMC); " 3°55.600'N, 56°11.300'W, 600 m/ CSNR: Tafelberg Summit, nr/ Augustus Creek Camp pools &/ creeks on trail into Arrowhead/ basin; leg. Short & Bloom/ 17.viii.2013; SR13-0817-01A" (3, SEMC); " 3°55.600'N, 56°11.300'W, 600 m/ CSNR: Tafelberg Summit/ nr Augustus Creek Camp/ 17.viii.2013; SR13-0817-03A" (26, NZCS, SEMC); " 3°53.942'N, 56°10.849'W, 733 m/ CSNR: Tafelberg Summit, near/ Caiman Creek Camp, stream/ margins; leg. Short & Bloom/ 18.viii.2013; SR13-0818-01A" (11, SEMC); same, except "forest detrital pools; SR13-0818-02A" (1, SEMC); same, except "pools in forest/ 19.viii.2013; SR13-0819-05B" (8, SEMC); same, except "margins & leaf packs in Caiman Creek/ SR13-0819-05D" (79, MIZA, MALUZ, SEMC); " 3°55.600'N, 56°11.300'W, 600 m/ CSNR: Tafelberg Summit, near/ Augustus Creek Camp, detrital/ creek; leg. Short & Bloom/ 22.viii.2013; SR13-0822-01A" (14, SEMC); same, except "leaf packs/ SR13-0822-03A" (1, SEMC).

Differential diagnosis.

Crucisternum vanessae is very similar to C. ouboteri and C. queneyi in the sharpness of the punctation and the general coloration of the body (compare Fig. 2E-H to 2A-D and Fig. 1E-H , respectively). It can be readily recognized by the pear-shaped aedeagus (as opposed to fusiform), with the apical third of the median lobe parallel-sided, as well as inwardly pointing apices of the parameres (Fig. 6D ).

Description.

Body length 2.0-2.5 mm, width 1.2-1.4 mm. General coloration dark brown on elytra, slightly paler on pronotum and head (Fig. 2E ). Elytra with punctures rather sharply marked. Aedeagus (Fig. 6D ) pear-shaped, widest at basal third; apex of parameres slightly pointing inwards; apical third of median lobe parallel-sided, nearly as wide as a paramere at the base of its apical third; gonopore located at apical third of median lobe.

Etymology.

Named after Surinamese entomologist Vanessa Kadosoe who has assisted us on numerous expeditions in Suriname, including the expedition to Tafelberg on which this species was discovered.

Distribution.

Currently known only from several streams on the summit of Tafelberg Tepui in central Suriname. Collected at elevations from 600 to 733 m. See Fig. 7 .

Biology.

This species was collected in several forested streams that drain the summit of a low-elevation tepui. Specimens were abundant in several spots, usually where lots of fallen leaves and detritus had accumulated along the stream margins. Specimens were collected by submerging the leaf packs and catching the specimens that floated to the water surface. See Fig. 8D .

Figures

Figure 1. Habitus of Crucisternum spp.: A-D Crucisternum escalera: A dorsal view B lateral view C ventral view D head E-H Crucisternum queneyi: E dorsal view F lateral view G ventral view H head. Scale bars: 1 mm.

Figure 2. Habitus of Crucisternum spp.: A-D Crucisternum ouboteri: A dorsal view, B lateral view C ventral view, D head E-H Crucisternum vanessae: E dorsal view F lateral view G ventral view H head. Scale bars: 1 mm.

Figure 6. Aedeagus of Crucisternum spp.: A-B Crucisternum ouboteri: A Guyana B Brownsberg C Crucisternum toboganensis D Crucisternum vanessae E-F Crucisternum xingu: E colln 6 F colln 23 G-H Cuscisternum sinuatus: G colln 23 H BR 18 - 0302 - 04 A I Crucisternum escalera J Crucisternum queneyi. Scale bars: 0.25 mm.

Figure 7. Distribution of Crucisternum species.

Figure 8. Habitat of Crucisternum spp. A-B Habitat for C. ouboteri Suriname, Raleighvallen, collecting event SR 12 - 0727 - 03 A C Type locality and habitat for C. ouboteri, Suriname, Brownsberg Nature Park, collecting event SR 12 - 0804 - 01 A D Type locality and habitat for C. vanessae, Suriname, Tafelberg Summit, Caiman Creek, collecting event SR 13 - 0819 - 05 D E-F Type locality and habitat for C. escalera, Venezuela, Bolivar State, along La Escalera, collecting event AS- 08 - 058.