Agabus puetzi, Fery, 2011

Fery, Hans, 2011, Agabus (Acatodes) puetzi sp. n., a new species of the confinis-group from the Qinghai-Tibet Plateau (Coleoptera, Dytiscidae, Agabini), Zootaxa 3050, pp. 37-54 : 38-44

Agabus puetzi sp. n.

Type locality. China, Sichuan province, Ganzi Tibetan Autonomic Prefecture, Batang County, Shaluli Mountains , Haizi mountain , 57 km NE Batang, route 318, km 3219, border of "Sister Lakes"; ca. 30.2990N 99.5527E, altitude ca. 4490 m (see Figs 40, 41) .

Holotype. ♂, " China, Prov. Sichuan, Ganzi Tibetian Auton. Pref., Batang Co., Shaluli Shan ", " Water Pools , 57 km NE Batang, route 318, km 3219, 4500 m, 3.VII.1999, leg. A. Pütz " [printed], " Holotype, Agabus puetzi sp. n., Fery det. 2011" [red, printed] ( CPE) . Paratypes: 1 ♂, 2 ♀♀, with same label data as holotype, but male with entire text on only a single label; all paratypes with the respective red paratype label ( CHF, CPE). Notes: The holotype lacks the left mid leg; the male paratype has the last three right protarsomeres and all left metatarsomeres disarticulated, and the sucker palettes of the protarsomeres are in part removed .

Description (holotype). Habitus rather flat, in dorsal view elongate oval, rather narrow (TL/MW: 2.08), with a distinct discontinuity in outline between pronotum and elytra ( Fig. 1). Broadest near middle of elytral length. Head and pronotum black, elytra dark brown; entire surface shiny although provided with a primary reticulation of larger meshes and in large parts with an additional secondary microreticulation.

Head black, except brown anterior margin and two indistinct round dark brown spots on vertex; labrum lighter brownish, contrasting distinctly with black clypeus. Bead on anterior margin of clypeus practically complete, consisting mostly of narrow, elongate, closely spaced and contiguous transverse punctures; bead slightly deviating backwards medially, interrupted over a very small distance, gap not much longer than diameter of meshes of primary reticulation on clypeus behind. Head behind clypeus with an oblique clypeal fovea on each side, consisting of about five impressed punctures and a distinct fine oblique groove stretching until lateral margin of clypeus; with several broad shallow pits and a few coarse punctures along inner side of eyes. Entire surface reticulated with not deeply impressed, more or less polygonal meshes, variable in shape and not isodiametric; strongly longitudinally stretched near eyes. Meshes behind clypeal foveae with microreticulation, but this becoming indistinct towards eyes and vertex. Punctation on head very sparse, some punctures inside meshes, others at intersections of reticulation lines and very few along these lines. Setae very sparse, confined to sides of anterior bead, clypeal foveae and pits near eyes.

Pronotum completely black. In dorsal view sides slightly curved in posterior two thirds, anteriorly almost straight. Posterior angles slightly obtuse, very narrowly rounded. Lateral bead well marked, vanishing far before anterior angle. Anterior margin not completely beaded, only behind eyes with a short line, near anterior angles and rest of margin without bead. Sublaterally with a shallow oblique impression; here and also near lateral bead with a few punctures. Near each posterior angle with another, but smaller and even shallower impression. Somewhat behind anterior margin with rather broad row of very irregularly arranged coarse punctures, these slightly sparser medially, but row not interrupted; another row of punctures before posterior margin, but punctures less numerous and slightly smaller; row broadly interrupted medially, but sublaterally not interrupted again, at least punctures somewhat sparser. Centre of pronotal disc with a rather long distinct single scratch. Primary reticulation similar to that on centre of head; anterior margin narrowly without reticulation, between this margin and anterior row of punctures meshes rather small; secondary microreticulation near sides and in particular at anterior angles. Punctation at intersections of reticulation lines and along these lines similar to that on head, several meshes also with such rather distinct punctures inside, but most meshes with several additional very shallow and almost imperceptible punctures; these becoming slightly more impressed posteriorly. Setae long, but very sparse, present only in a few coarser punctures near anterior and posterior margin and in sublateral impressions.

Elytra dark brown; behind base, near lateral margins and in anterior half along suture diffusely delimited lighter brownish; scutellum, elytral base centrally and suture itself black. In dorsal view sides in anterior two thirds slightly rounded, not continuing curvature of pronotum, more strongly curved behind, conjointly rounded at apex. Margin of elytra in lateral view almost straight in anterior two thirds, not considerably ascending to shoulders. Lateral rim distinctly narrower than that of pronotum. Each elytron with a large subapical oblique impression, margin at apex thus appearing somewhat vaulted. Each elytron with four irregular puncture lines, starting short behind elytral base; in second third of elytral length with a few additional punctures between lines, in apical fourth lines becoming very irregular; sutural puncture lines only indicated by very few small punctures behind first third of elytral length; diameter of punctures much smaller than that of primary meshes. Directly beside lateral elytral rim with a fifth puncture line. Primary reticulation similar to that on head and pronotum; meshes smaller near suture and in subapical impressions. Secondary microreticulation present on entire surface, slightly more distinct in subapical impressions (reticulation similar to that in Figs 5 and 6 in Larson (1989: 905) for Agabus (Gaurodytes) ambiguus (Say, 1823)) . Setation very sparse and indistinct, more or less only perceptible with oblique illumination; restricted to punctures within lines. Setae often rather long (up to seven meshes in length), in particular in lateral puncture line and apical third of sublateral puncture line (also up to seven meshes in length).

Ventral surface with major parts black; apex of metacoxal processes and posterior margins of third to sixth abdominal ventrites transparently brownish; epipleura black in broad anterior half, near shoulders somewhat transparent dark brownish, in small posterior half dark brown. Head with most mouthparts brown, mentum, gula and genae black. Legs and trochanters reddish brown, femora largely darkened medially. Antennomeres reddish brown, progressively darkened distally, beginning with fifth; second antennomere short, third longer than second and fourth, fourth only indistinctly shorter than fifth. Maxillar and labial palpi reddish brown, apical palpomeres diffusely darkened medially. Before procoxae outline of prosternum and prosternal process in lateral view more or less straight, slightly descending backwards, almost imperceptibly impressed directly before procoxae, but process not stepped down from plane of prosternum; lanceolate blade bent upwards shortly behind middle of procoxae. Blade broad, rather flat, evenly vaulted in cross-section; sides not flattened; bead being only a thin but distinct line; apex bluntly pointed, not acuminate ( Fig. 10). Process between procoxae indistinctly tectiform in cross-section, but midline of convexity broadly rounded; before procoxae evenly and broadly rounded in cross-section. Distance between mesocoxae rather small, smaller than width of process between procoxae. Anteromedial metasternal process short, bluntly pointed anteriorly, not reaching forwards beyond middle of mesocoxae and not reaching mesosternum ( Fig. 10). Mesosternum before mesocoxae with a deep broad furrow for reception of prosternal blade ( Fig. 10). Apex of blade just contacting apex of anteromedial metasternal process, but not reaching further backwards than middle of mesocoxae, and, thus, not received in furrow on anteromedial metasternal process. This latter furrow being only a very shallow longitudinal impression, reaching more or less from apex of anteromedial metasternal process backwards until shortly before level of hind margin of mesocoxae ( Fig. 10). Lateral lobes of metasternum ("metasternal wings") rather broad (WC/WS: 2.26). Lines of metacoxal processes diverging anteriorly, reaching posterior margin of metasternum. Posterior margin of last abdominal ventrite evenly rounded.

Almost entire surface microreticulated, weakly shiny, but not matt; only midline of metasternum narrowly smooth, same with apical lobes of metacoxal processes. Meshes of primary reticulation only indicated on last abdominal ventrite, otherwise absent or incomplete on abdominal ventrites, in part replaced by some stronger impressed wrinkles. Lateral lobes of metasternum with some weak longitudinal rugae, sides of metacoxal plates with transverse rugae. Prosternum rugosely sculptured anteromedially; punctation of ventral surface very sparse and weak. Some fine punctures on blade of prosternal process, others at wrinkles of metacoxal plates; third to fifth abdominal ventrites with indistinct transverse row of setose punctures, last ventrite posteriorly with some stronger punctures.

Setae on ventral surface very sparse, short setae only present on mentum and on prosternum anteromedially; rather long setae emanating from a few punctures anteromedially on metasternum, apex of metacoxal processes, and third to sixth abdominal ventrites. Metafemora ventrally with a series of spaced rigid and transparent setae at posteroapical angle, typical for Agabini. Length of longer spur of metatibiae about 3/4 that of first metatarsomere.

Males: Protibiae proximally rather thin, distally broad; inner outline distinctly and very characteristically curved ( Fig. 3). First three pro- and mesotarsomeres strongly enlarged, provided with very dense setae on underside, each ending in a small elongate eccentrically stalked sucker palette; structure similar to that of A. zetterstedti Thomson, 1856 (cf. Fig. 58 in Larson 1989: 914), but palettes more elongate and much more numerous in A. puetzi sp. n.; those of third protarsomeres reaching so far forwards that fourth ones also appear as to be provided with sucker setae; however, fourth tarsomeres less enlarged and without adhesive setae. Fifth pro- and mesotarsomeres long, almost as long as respective first four tarsomeres together; underside with two rows of small bristles, somewhat more irregular on fifth mesotarsomere; fourth protarsomeres on underside only with a few bristles distally, fourth mesotarsomeres with two distinct rows of bristles. Pro- and mesotarsal claws shorter than respective fifth tarsomere; claws very weakly curved proximally, more strongly curved near apex; posterior claws slightly shorter. Metatarsal claws evenly and slightly curved, equal in length, and only half as long as pro- and mesotarsal claws. Mesotibiae and first mesotarsomeres with natatorial setal fringe ventrally. Fifth to ninth antennomeres with anteroapical angle slightly produced and truncate, here with a sensory seta; structure less distinct on tenth antennomeres, third and fourth not produced. Median lobe asymmetric, bent to left before apex; ventral groove open over entire length. In lateral view right side of apical fourth broad, left side thin ( Figs 5, 6, 31). Apex without a subapical dorsal spine, but right side before apex with a weak swelling (indicated by the arrow in Fig. 7). Parameres ( Fig. 8) stylate (or style-like; in contrast to strap-like; cf. Larson et al. 2000: 481).

Females: Both females studied with matt elytra; colour of elytra lighter than in males, head and pronotum as in males ( Fig. 2). Reticulation double, principally as in males, but secondary one on elytra somewhat more deeply impressed and surface of micro-meshes not shiny. Head and pronotum shiny, secondary reticulation on pronotum extended on entire surface except a small area around discal scratch. Ventral surface same as in males, except central part of metasternum more matt. Inner outline of protibiae less curved than in males, nevertheless, characteristic shape well recognisable ( Fig. 4). Pro- and mesotarsomeres not broadened, without sucker palettes; pro- and mesotarsal claws shorter and evenly curved; posterior protarsal claw slightly shorter than anterior one; metatarsal claws as in males, distinctly shorter than pro- and mesotarsal claws. Fifth pro- and mesotarsomeres rather long, but shorter than those of males. First pro- and mesotarsomeres anteriorly with one row of spines, posteriorly only distally with a few spines; on second to fourth pro- and mesotarsomeres both rows reduced to a few spines distally; fifth pro- and mesotarsomeres with two rows of spines. Mesotibiae and first mesotarsomeres ventrally without natatorial setal fringe (lack of this fringe in females being characteristic for part of Agabini, particularly for genus Agabus ; cf. Nilsson 2000: 18). Fifth to ninth antennomeres with sensory seta at anteroapical angle, but characteristic shape of angle in males only very indistinctly indicated in females. Female genitalia ( Fig. 9: (a) gonocoxa, (b) tergite 9) without conspicuous differences to those of e.g., A. congener (Thunberg, 1794) , A. lapponicus (Thomson, 1867) , A. zetterstedti or indeed A. arcticus (Paykull, 1798) , latter being member of the arcticus -group (cf. Fig. 54 in Larson 1989: 913).

Measurements. Holotype (male): TL = 7.5 mm, TL-h = 6.7 mm, MW = 3.6 mm, TL/MW = 2.08, WC/WS = 2.26; male paratype: TL = 7.2 mm, TL-h = 6.4 mm, MW = 3.5 mm, TL/MW = 2.06, WC/WS = 2.13; female paratypes: TL = 6.95/ 7.1 mm, TL-h = 6.2/ 6.4 mm, MW = 3.45/ 3.5 mm, TL/MW = 2.01/2.03, WC/WS = 2.13/2.04.

Variability. I have not found considerably variable features in the four specimens studied. The extent of the dark brown coloration on the elytra varies a little, the male paratype has the elytra somewhat transparent anteriorly, and the sides of the pronotum can be slightly less curved. The male paratype and one female have an additional shallow impression in the posterior half of the pronotum on each side of the mid line. The furrow on the anteromedial process of the metasternum is weaker in one female, and more strongly impressed in the male paratype. The width of the metasternal wings also varies a little; according to the measurements, the WC/WS ratio is smaller in females, but the few specimens studied do not allow a well-founded statement.

Distribution. Eastern Qinghai-Tibet Plateau; so far A. puetzi sp. n. is only known from the locus typicus. Lance He ( China) communicated the following information about the area, which includes the locus typicus (slightly modified by me): The Shaluli Mountains cover a large area in western Sichuan, which is more than 1000 km long. It's a part of the huge Hengduan Mountains, which lie across western Sichuan, north-western Yunnan and eastern Tibet. "Haizi" means in Tibetan "small lake in the mountain". Our Haizi mountain, or better the "Haizi peak", is just a small peak in southern Shaluli Mountains and it is named after the small twin lakes in front of it (it also has other names: Xiashe Peak, Peak Nitekhangri). There are several "Haizi peaks" known in western Sichuan, our peak is located in Batang county, another one in Daocheng county etc. All of them have some small lakes closely situated, thus, "Haizi peak" is a common name for this kind of mountain. Our peak is so well known because it's so close to the Sichuan – Tibet highway. Actually there are plenty of gorgeous mountains in Sichuan province, but many of them are not very accessible.

Derivatio nominis. The new species is named after Andreas Pütz (Eisenhüttenstadt, Germany), specialist in Byrrhidae and collector of the specimens. The specific epithet is a noun in the genitive case.

Biology. The specimens were found near the border of the "Sister Lakes" ( Figs 40, 41), in small pools of variable size (diameter ca. 0.5 m – 1 m, depth not more than 1 m), with coarse gravel on the ground, and without any vegetation, except some fine roots of small willows growing at the edge of the pools. The collector suspects that once during an earthquake big rocks fell down from the nearby mountain slopes and formed these little pools. The water was crystal clear and "very very cold" (temperature not measured). Other beetles found: Agabus longissimus Régimbart, 1899, 1908 , Boreonectes emmerichi (Falkenström, 1936) (formerly in Stictotarsus Zimmermann, 1919 ; see Angus 2010), Hydroporus tibetanus Zaitzev, 1953 , and Helophorus spec. ( Hydrophilidae , Helophorinae ).