Sphaeridium daemonicum, Fikáček & Kropáček, 2015

Fikáček, Martin & Kropáček, Daniel, 2015, A new species of Sphaeridium from northeastern India and Myanmar (Coleoptera: Hydrophilidae: Sphaeridiinae), Acta Entomologica Musei Nationalis Pragae 55 (2), pp. 673-680 : 674-679

Sphaeridium daemonicum sp. nov.

( Figs 1–11 )

Type locality. India, Arunachal Pradesh State, 3.6 km NW of Bhalukpong, 280 m a.s.l., 27°01ʹ57ʺN 92°36ʹ24ʺE.

Type material. HOLOTYPE: J ( NMPC): “INDIA: Arunachal Pradesh (16) / 3.6 km NW of Bhalukpong / 7.v. 2008, 280m / 27°01ʹ57ʺN 92°36ʹ24ʺE / Fikáček, Podskalská, Šípek lgt. // cow excrements on the road / in secondary tropical evergreen / forest” . PARATYPES: INDIA: 1 J ( NMPC): same label data as the holotype. MYANMAR: 3 JJ ( NMPC): “TENASSERIM, Birmania / coll. J. V. Helfer / National Museum Prague”.

Description. Body widely oval, rather depressed in lateral view. Body length 3.7–4.4 mm (holotype: 4.2 mm), body width 2.7–3.1 mm (holotype: 3.0 mm).

Coloration. Dorsal surface of head black, with minute vaguely defined reddish spots anterior to each eye; labrum reddish brown ( Fig. 4 ). Pronotum black, lateral margin with a wide sharply delimited yellowish stripe ca. 4–5× wider than the lateral marginal bead; border of the yellow spot sinuate posteriorly ( Fig. 2 ). Elytra dark brown to black, with a large yellowish spot extending over apical third of elytra and reaching ca. elytral midlength along suture, laterally almost reaching elytral base on lateralmost interval ( Figs 1–2, 5 ); epipleuron yellow. Ventral surface yellowish with the following pattern of darker spots ( Fig. 3 ): head blackish in anterior part of mentum, at anterior margin of submentum and along gular sutures; ventral surface of mesothorax with darker portions laterally of mesoventral elevation; metaventrite with black pentagonal central spot and black stripes along anterior and lateral margins, parallel to posterior margin, and on each side one additional arising posterolaterally of central pentagon and reaching ca. 0.75 of distance towards anterolateral corner (when combined, metaventrite bears an apparent trilobate dark spot); metanepisterna each with dark spot centrally. Abdominal ventrites largely yellow, ventrites 2–5 each with a narrow dark stripe along anterior margin slightly extending laterally ( Fig. 11 ). Maxillary palpi reddish brown. Antennomeres 1–5 brownish, antennal club black. Legs yellow, meso- and metafemur each with a darker (brownish) central rounded spot; tibiae bearing strong dark spines; meso- and metatarsi slightly darker than femora and tibiae, reddish brown; protarsus yellow. Hind wings darkly tinted.

Morphology. Head. Dorsal surface with moderately dense uniform punctation consisting of minute sharply impressed punctures mixed with few slightly larger punctures both on clypeus and frons; interstices without microsculpture; frontal sutures distinct as bare stripes lacking punctation. Eyes small, deeply excised on anterior margin, interocular distance 6.8× the maximum width of one eye. Labrum largely exposed, straight on anterior margin, pubescent anteriorly, microreticulate. Mentum ca. 2× wider than long, bisinuate on anterior margin, lateral margins convex; surface with weak moderately dense setiferous punctation, interstices with a sculpture consisting of transverse ridges anteriorly. Antennal club rather compact.

Prothorax. Pronotum with a deeply bisinuate posterior margin; posterolateral corners rectangular. Punctation of pronotum uniform, moderately dense, similar to that on head. Pronotal interstices without microsculpture. Marginal bead very wide at lateral margin and extremely narrow along anterior margin, posterior margin without marginal bead. Lateral margin with a series of small but stout spines. Prosternal process wide and slightly convex at the base and long, bearing 6 strong spines mesally, and a large spine on its apex.

Mesothorax. Mesoventrite with a rather high median elevation bearing numerous strong spines. Scutellar shield 2.3× longer than wide. Elytra rounded separately at apex, each with a wide marginal bead along lateral and anterior margins; lateral margin with a series of small but stout spines. Each elytron with 10 well developed even though sometimes rather irregular elytral series, series 1 in apical two thirds contiguous with sharply impressed sutural stria; sutural stria connected to marginal elytral bead ( Fig. 5 ). Serial punctures ca. 3× as large as interval punctation and hence easily distinguishable from general punctation, except laterally.

Metathorax. Metaventrite with distinct median distrimen; median portion glabrous, bearing sparse punctation, interstices with strong microsculpture consisting of transverse ridges; lateral portions of metaventrite with dense and coarse punctation, densely pubescent. Metathoracic wings well developed.

Legs. Procoxa on dorsal surface with numerous long spines. Profemur ventrally densely pubescent except on apical fifth. Protibia with numerous large stout spines. Male protarsus modified, with tarsomeres 1–4 shortened and slightly widened, ca. subequal in length, tarsomere 5 ca. as long as tarsomeres 1–4 combined, ca. 1.5× longer than wide ( Fig. 9 ). Anterior claws inequal; the larger claw wide, strongly bent, blunt at apex in lateral view, with a distinct spine on mesal margin; the other claw small, tiny, regularly arcuate. Mesofemur base with moderately dense spiniferous punctation, intervals with microsculpture consisting of transverse ridges; metafemur with sparse spiniferous punctations, intervals with sculpture as in mesofemur. Both meso- and metatibia with numerous long and stout spines, each with two spines on ventral surface. Meso- and metatarsus with basal tarsomere nearly as long as tarsomeres 2–5 combined, on ventral face bearing a series of stout spines and ventral pubescence; tarsomeres 2–4 with ventral pubescence only; claws simple, regularly curved.

Abdomen with 5 ventrites, basal ventrite without median carina; all ventrites completely covered by dense pubescence; abdominal apex entire, without apical emargination.

Male genitalia ( Figs 6–8 ). Aedeagus 1.35–1.50 mm long (holotype: 1.35 mm). Median lobe much longer than parameres, slightly widening from base to ca. midlength, slightly constricted in apical fourth and then again slightly widened subapically; apex of median lobe arcuate, with apical subrectangular projection, gonopore subapical. Paramere with narrow dorsal portion and wide ventral portion, and hence partly enveloping median lobe; apex with a series of stout setae on the ventral portion. Phallobase very short, asymmetrical.

Sexual dimorphism. Female unknown.

Variation. All examined specimens are very similar to each other in most characters, with the only variation observed being in the extent of the dark coloration on the base of abdominal ventrites (the dark spot may be very narrow and nearly without the lateral extensions, or with very distinct lateral and smaller sublateral extensions as in Fig. 11 ), in the number of strong spines on the median portion of the prosternum (4–6 spines are present in examined specimens), and in the intensity of the dark spot on meso- and metafemora (rather inconspicuous in a single slightly teneral specimen).

Differential diagnosis. The new species may be easily recognized from other Oriental species of the genus based on its small body size, elytra with sharply delimited yellow spot in apical third ( Figs 1–2, 5 ) and pronotum with a wide yellow lateral stripe on each side ( Fig. 2 ), the yellow coloration of the ventral surface with a characteristic trilobed spot on the metaventrite ( Fig. 3 ), rectangular posterolateral corners of the pronotum, the aedeagus with wide parameres enveloping the median lobe ( Figs 6, 8 ), and the median lobe slightly constricted and then subapically widened ( Fig. 6 ). It is unique among Oriental species also in lateral margin of pronotum and elytra bearing a series of small spines ( Fig. 10 ).

The majority of the Oriental-Australian Sphaeridium is characterized by long and very narrow apical portion of paremeres, which are not enveloping the median lobe. Of these species, S. dimidiatum Gory, 1834 and S. discolor Orchymont, 1933 differ from the new species also by obliquely cut off posterolateral corners of the pronotum and the dark general coloration of the ventral surface. The species of the S. seriatum species group ( S. seriatum Orchymont, 1913 , S. reticulatum Orchymont, 1929 , S. severini Orchymont, 1919 , S. vitalisi Orchymont, 1925 and probably also S. kolleri Orchymont, 1925 ) also bear long and very narrow parameres, but otherwise they may resemble the new species by the elytral coloration and the generally yellow ventral body surface with dark patterns. All these species are however much larger (> 6.0 mm) and can be easily distinguished by the abdominal ventrites bearing alternating yellow and dark patches on each ventrite, which gives the whole abdomen a checkboard pattern. The species of this group in which males are known ( S. seriatum , S. reticulatum , S. severini ), moreover differ also by the shape of the median lobe. The New Guinean species S. huijbregtsi and S. flavomaculatum Orchymont, 1924 also differ from the new species by narrow parameres, larger body size, abdominal ventrites with black spots rather than dark on the anterior margin, and also by the yellow anterior portion of the head.

Sphaeridium quinquemaculatum is the only Oriental species which is comparable to the new species in size, and has parameres enveloping the median lobe, albeit being rather narrow apically. The species is, however, easy-to-distinguish from S. daemonicum sp. nov. based on elytral coloration (with additional set of reddish spots anterior of the yellow apical spot, often merging into a single large yellowish-reddish multilobate spot, rarely these spots are missing), the mostly dark coloration of the ventral surface, meso- and metafemora lacking the dark central spot, and ventral face of metatibia usually bearing a single spine. The aedeagus, albeit rather similar to S. daemonicum on the first view, has longer and narrower parameres and its median lobe is more parallel-sided, lacking the subapical constriction characteristic for S. daemonicum .

The only other Oriental species similar to S. daemonicum seems to be an undescribed species also found among the material from Tenasserim collected by J. V. Helfer in NMPC. This species is very similar to S. daemonicum in most aspects including the wide parameres enveloping the median lobe and the general coloration. In contrast to S. daemonicum , the species has a different median lobe (more parallel-shaped and rounded and apex), the prosternal process bears less and shorter spines, and the ventral portion of the metatibia bears 3 spines. The species is not described here pending the discovery of more recently collected specimens. When compared to the Afrotropical species of S. simplicipes group (with which S. daemonicum shares the small body size and presence of small spines on lateral pronotal margin), the new species easily differs from all species but S. bottegoi Marcuzzi, 1943 by the presence of two spines on the ventral surface of metatibiae, and from all species by the genital morphology ( BERGE HENEGOUWEN 1992).

Etymology. The species name is the Latin adjective daemonicum (- us, - a, - um) (= demonic, devilish) referring to the characteristic color pattern of the metaventrite of the new species, which resembles the horns of a hellʼs demon.

Biology. Both Indian specimens were collected in cow dung in secondary evergreen tropical forest, together with an aberrant specimen of S. quinquemaculatum (in terms of color pattern of elytra and quite large body size). The area in which the specimens were collected is the part of the lowland Brahmaputra valley. No biology data are known for historical specimens examined.

Distribution. Recently collected in the Brahmaputra valley (lowland portion of Arunachal Pradesh, India). Three historical specimens examined by us were collected by the Czech doctor, traveller and entomologist J. V. Helfer in Tenasserim (i.e. the present-day Tanintharyi Region in southern Myanmar), where he worked and collected in years 1837–1838. The specimens were originally deposited in a historical cabinet only containing Helferʼs specimens from Tenasserim donated to the National Museum by Helferʼs wife Paulina in 1843, which however did not bear any locality labels; these were added recently when the specimens were transferred to modern entomological boxes. Since Helfer collected also around Kolkata where he lived before starting his work in Tenasserim, and to where he was occasionally returning even during the years spent in Tenasserim (HELFER- NOSTITZ 1878), we cannot totally exclude the possibility that the three historical paratypes of S. daemonicum sp. nov. were collected in around Kolkata and not in southern Myanmar, despite being labelled as such. On the other hand, since the species occurs in lowlands and all Sphaeridium species are quite widespread ( HANSEN 1999), the occurrence of S. daemonicum sp. nov. in northeastern India and southern Myanmar seems also easily possible.

Figures

Figs 1–5. Holotype of Sphaeridium daemonicum sp. nov. 1 – dorsal view; 2 – lateral view; 3 – ventral view; 4 – detail of head and anterior leg; 5 – elytral apex.

Figs 6–11. Sphaeridium daemonicum sp. nov. (6–10 – holotype, 11 – paratype from Tenasserim): 6 – aedeagus; 7 – apex of the median lobe; 8 – apex of paramere; 9 – protarsus (only tarsomeres 3–5 shown); 10 – lateral margin of pronotum; 11 – abdominal ventrites.