Incoltorrida quintacostata, Perkins & Bergsten, 2019

Perkins, Philip D. & Bergsten, Johannes, 2019, New Myxophagan water beetles from Madagascar (Coleoptera: Torridincolidae, Hydroscaphidae), Zootaxa 4657 (1), pp. 57-96 : 68-70

Incoltorrida quintacostata , new species

Figs. 2 , 7 (habitus), 17, 18 (genitalia), 23 (larva), 34 (map), 42, 43 (habitat),

Type Material. Holotype (male): Fianarantsoa, 3.5km N Ivato , 20º 35.844’ S 47º 12.78’ E, rock face seep beside hwy. 7, elev. 1471 m, 5 xi 2014, P. D. Perkins ( NHRS).

Paratypes (193): Same data as holotype (19: NHRS, MCZ) ; Antsiranana, Anjiabe Ambony: Ambilobe: Antsabe stairways-like cascade with vertical (!) steps, exposed, extremely hot day, N: -13.60930 E: 48.72120, elev. 303 m, 23 xi 2004, Balke et al. (P25 MD16 ) (8 BMNH; 2 DNA extractions, #’s BMNH 670734 , BMNH 670735 ) ; Diana: Antsaba: Galoko mountains , 3.4 km NW from Anstaba , S13.60931 E48.72129, aspirator, forceps, sieves: hygropetric rocks and pools, elev. 296 m, 28 xi 2012, elev. 296 m, 28 xi 2012, J. Bergsten, R. Bukontaite, J.H. Randriamihaja & T. Ranarilalatiana ( MAD12-31 ) (5 NHRS) ; Diana: Antsaba: Galoko mountains , S13.60974 E48.72175, sieves and aspirator: hygropetric rocks and water pools, elev. 263 m, 25 xi 2012, J. Bergsten, R. Bukontaite, J.H. Randriamihaja & T. Ranarilalatiana ( MAD12-26 ) (62 NHRS, BMNH, PBZT / MBC) ; Fianarantsoa, 3.2km S Ambohimanjaka , 20º 14.0343’ S 47º 5.59145’ E, waterfall and hygropetric habitat near hwy. 7, elev. 1415 m, 5 xi 2014, P. D. Perkins (95 NHRS & MCZ) ; Atsimo Antsinanana: R.S. Manombo: Parcelle I, Rearatra , Piste 56: S23.006183 E47.7338833, GB nets and sieves, forest stream with pools, elev. 21 m, 14 xii 2013, J.H. Randriamihaja & T. Ranarilalatiana ( MAD13- 73 ) (3 NHRS) ; 20.7722S 47.1809E; Amoron’i Mania, 3km south of Ambalamanakana next to RN7, Ankazomivady forest , hygropetric rocks and marsh with vegetation, elev. 1700 m, 1 xi 2014, J. Bergsten, T. Ranarilalatiana & S. Holmgren ( MAD 14-02 ) (1 NHRS).

Differential Diagnosis. Differentiated from all other known Incoltorrida , except I. galoko , by the elytral sculpture. Each elytron has only five costae: #1, #2, #3, #5, and #8; costa #4, #6, and #7, which are present in other species, are absent in I. quintacostata ( Fig. 2 ). The serial punctures are minute and very indistinct (microslide preparation necessary to see the punctures clearly). In this species the elytral costae are well developed in height, but comparatively narrow; the areas between the costae are quite flat. The transverse ridge that connects elytral costae #5 and #8 is more or less distinct (depending on the population). The anterior depressions of the pronotum are well developed and the foveae forming the medial margins of the ridges are narrowly separated and the intervening surface is transversely rounded, but there is no separate median carina. The pronotal sculpture and adult size of I quintacostata differ markedly from those of I. galoko , which also has five costae of each elytron. The ridges and impressions of the pronotum are similar to those of I. benesculpta , a much smaller species that has very different elytral sculpture; the aedeagi of the two species markedly differ ( Figs. 18 , 20 ).

Description. Size: holotype (length/width, mm): body (length to elytral apices) 2.33/1.32; head width 0.47; pronotum 0.51/0.93, elytra 1.50/1.32. Dorsum dark brown to black, venter brown to dark brown, legs brown except femoral-tibial articulations and tarsi black.

Sides of frontoclypeal shield very slightly arcuate, almost parallel-sided, and only very slightly and gradually narrowed from frons vertex to the transverse anterior margin of the clypeus.

Short oblique carinae on anterior 1/3 of pronotum are well developed; no indication of a midlongitudinal carina. Basal 1/3 of pronotum with distinctive carina on each side, each slightly oblique toward midline.

Each elytron with only five costae: #1, #2, #3, #5, and #8; costae #4, #6, and #7 absent. Areas between costae quite flat, and serial punctures minute, very indistinct, a unilinear row located adjacent to the lateral margin of each costa. Transverse ridge linking costae #5 and #8 present, but more distinctive in some populations than others.

Lateral margins of the metaventral tabella straight for most of their length, arcuate only very near base. Midlongitudinal groove in posterior 1/2 of the metaventral tabella is narrow and parallel-sided.

Midlongitudinal carina of the first abdominal ventrite is moderately strong but usually does not extend the full length of the ventrite.

Male genitalia long and slender ( Figs. 17, 18 ); see remarks.

Etymology. Named in reference to the five costae of each elytron.

Remarks. Some specimens, such as the holotype, have the posterior angles of the pronotum very weakly shallowly notched; other specimens do not have this weak indentation, and some specimens have it only on one side.

The male genitalia in ventral view is long and comparatively slender, with a quite spinose apical tip ( Figs. 17, 18 ). Males vary considerably in body length, ca. 2.09–2.39 mm. The length of the aedeagus varies, roughly, in proportion to the body size; for example: (aedeagus length/body length): 0.73/2.18 (=0.33); 0.75/2.15 (=0.35); 0.77/2.09 (=0.37);0.80/2.24 (=0.36); 0.93/2.39 (=0.39, the holotype). The shape of the aedeagus does not vary significantly. This is the most commonly collected species of Incoltorrida ( Fig. 34 ).

Four larvae ( NHRS) were collected at the type locality, and 54 larvae ( NHRS) were collected at site MAD 12- 26.

DNA sequences of partial CO1 (Acc. Nos. FJ819700 ( BMNH 670734) and FJ819701 ( BMNH 670735)) and partial 28S ( FJ 818156 ( BMNH 670734) and FJ818157 ( BMNH 670735)) published by Monaghan et al (2009) are based on adult specimens, and are available in Genbank.

Figures

FIGURE 7. Incoltorrida quintacostata, habitus views of holotype.

FIGURES 2–4. Dorsal morphology. (2) Incoltorrida quintacostata; (3–4) I. magna.

FIGURES 14–18. Incoltorrida spp.; (14) I. madagassica, male genitalia of holotype (after Steffan 1973, permanent slide mount). (15–17) male genitalia apex showing pores of I. madagassica and spines of I. benesculpta and I. quintacostata; (18) I. quintacostata, aedeagus of holotype.

FIGURES 19–20. (19) Incoltorrida madagassica, male genitalia of non-type; (20) Incoltorrida benesculpta, male genitalia of holotype.

FIGURES 34–37. Incoltorrida distribution maps.