Microdytes svensoni Miller & Wewalka

Miller, Kelly B. & Wewalka, Günther, 2010, Microdytes Balfour-Browne of India with description of three new species (Coleoptera: Dytiscidae: Hydroporinae), Zootaxa 2420, pp. 26-36 : 27-28

Microdytes svensoni Miller & Wewalka , new species

Type locality. India, Karnataka, 30km E Udupi.

Material examined. Holotype ♂ ( MSBC), “ INDIA: Karnataka forest stream 30km E Udupi [13°29’27.8’’N 75°04’14.89’’E] 0 4 Oct 2004. KB Miller, colr./ HOLOTYPE: Microdytes svensoni Miller & Wewalka, 2009 [red label with double black line border].” Paratypes, 33 ex. from same locality and data as holotype ( MSBC, USNM); 76 ex. INDIA: Karnataka, Coorg, Kakkabe env., 21-25. xii. 1998, 12 °15’N 75°35’E, 900 - 1200 m, leg. D. Boukal (loc. 11, 12, 18, 21) ( CGWW, MSBC, NHMW, NMPC). All paratypes are provided with red printed paratype labels.

Additional specimens. 1 ♂, 1 ♀, INDIA, Kerala, Kallar Valley, 10 km WSW Munnar, 1100 m, 10°03’N 76°58’E, 7. 1. 1999, leg. D. Boukal (50) ( CGWW, NHMW); 2 ♂, 1 ♀, INDIA, Tamil Nadu, Palni Hills, Kodaikanal env., Vellagavi, 900 m, 10°11’N 77°29’E, 13. 1. 1999, leg. D. Boukal (62) ( CGWW, NHMW).

Diagnosis. M. svensoni is very similar to M. belli in habitus, size, coloration and male genitalia. It differs from this species by the more sparse and less regular punctures of the pronotum, the punctures of the elytra consisting of two kinds, and the median lobe of the male genitalia less broad medially as seen in lateral aspect. Microdytes svensoni is also similar to M. sabitae but it is smaller and the yellowish-brown maculae are much less extensive.

Description. Measurements. TL = 1.55–1.80 mm, GW = 1.15–1.30 mm, TL/GW = 1.30–1.36. Body robust, globular, strongly rounded; lateral outline slightly constricted between pronotum and elytron; lateral margins of elytron broadly curved ( Fig. 1 ).

Coloration. Head red-brown, blackish along posterior margin. Pronotum red-brown to dark-brown, ligher at lateral sides. Elytron dark brown with small, yellowish maculae, a macula present at humeral angle and one present medially along margin; these maculae connected along margin; additional small, yellow maculae present medially on disc and subapically ( Fig. 1 ). Prothoracic sterna and ventral surfaces of head yellow; meso- and metathoracic sterna, metacoxae and abdominal ventrites red-brown; legs, antennae and palpi yellowish-brown.

Sculpture and structure. Head with fine, inconspicuous, irregular punctation; other microsculpture absent; anterior clypeal margin with thick marginal bead, indistinct; eyes medium in size. Pronotum somewhat more strongly punctate than head, with coarse punctures along posterior margin, without other microsculpture; with posterior angles weakly produced posteriorly; lateral bead of even width throughout. Elytron with punctation moderately dense, irregularly distributed, consisting of coarse and fine punctures; discal series of punctures present; dorsolateral series of punctures present, indistinct; without other microsculpture; anterolateral angle not extended anteriorly. Lateral part of metaventrite, metacoxae and lateral part of abdominal ventrite I and II coarsely and regularly punctate; rest of abdomen without punctation; ventral side without other microsculpture.

Male genitalia. Median lobe in ventral aspect ( Fig. 5 a), lateral aspect ( Fig. 5 b). Lateral lobes in ventral aspect fused ( Fig. 9 a), lateral aspect ( Fig. 9 b).

Variation. This species varies in the extent of the elytral maculae with some specimens with the maculae extensive and covering much of the elytron and others reduced such that the medial macula is nearly absent. In specimens from Kerala and Tamil Nadu the elytral punctures are of two kinds but the coarser punctures are somewhat finer and the punctures of metacoxae are less course than in the paratypes and the yellowish elytral maculae are somewhat more extended. As no significant differences in male genitalia have been found these specimens are assigned to M. svensoni but not included in the series of paratypes.

Etymology. This species is named in honor of esteemed colleague, G.J. Svenson, Albany, NY, USA.

Habitat. This species was collected in small forest streams mostly in muddy or gravelly, shallow, stagnant shore parts, rather shaded.

Distribution. India: Karnataka, Kerala, Tamil Nadu ( Fig. 13 ).

Figures

FIGURE 13. Distribution of Microdytes in India.

FIGURES 1 – 4. Dorsal habitus and variations of color patterns of Microdytes species: 1) M. svensoni; 2) M. cameroni; 3) M. whitingi; 4) M. sabitae.

FIGURES 5 – 8. Median lobe of aedeagus: a) dorsal aspect, b) right lateral aspect: 5) M. svensoni; 6) M. cameroni; 7) M. whitingi; 8) M. sabitae.

FIGURES 9 – 12. Lateral lobes of aedeagus: a) dorsal aspect, b) lateral aspect: 9) M. svensoni; 10) M. cameroni; 11) M. whitingi; 12) M. sabitae.