Ancyronyx buhid Freitag

Freitag, Hendrik, 2013, Ancyronyx Erichson, 1847 (Coleoptera, Elmidae) from Mindoro, Philippines, with description of the larvae and two new species using DNA sequences for the assignment of the developmental stages, ZooKeys 321, pp. 35-64 : 48-55

Ancyronyx buhid Freitag sp. n. Figs 4, 7, 13 A–P, 14 A–I

Etymology.

The species is named for the indigenous ethnic group of the Buhid in whose ancestral areas it commonly occurs. Same time, their kind support and care during regular field trips of faculty members and students of the Ateneo de Manila University’s Biology Department to the their Ancestral Domain should be honoured. Buhid is used as noun in apposition.

Type material.

Holotype♂ (NMW) "leg. Jäch 1.12. \ PHILIPPINEN - Mindoro \ 20km W Calapan 1992 \ Hidden Paradise (21)", terminal parts of abdomen incl. aedeagus glued separately. Paratypes: 11 ♂♂, 23 ♀♀, 6 L (3 × 0.29, 2 × 0.30, 0.31) (NMW): same data as holotype. 8 L (2 × 0.29, 0.30, 4 × 0.31, 0.32) (NMW) "PHILIPPINEN - Mindoro \ 20km W Calapan 1992 \ Hidden Parad. 20.-21.11. \ leg. Jäch(10)”; 4 ♀♀ "PHILIPPINEN - Mindoro \ 20km W Calapan 1992 \ Hidden Parad. 20.-21.11. \ leg. Schillhammer (10)"; 3 ♂♂, 3 ♀♀ (CZW) "PHIL.: Mindoro or. \ Baco, Hidden Parad. \ 19.-20.11.1993 \ leg. Zettel (27)"; 7 ♂♂, 4 ♀♀, 4 L (0.27[FR091]), 2 × 0.31, 0.29) (SMTD) "PHIL.: Mindoro, Baco, Dulangan, Lantuyan torrent mount.Riv.; sec.veget.; riffle, wood debris, c. 55m asl., c. 13°16'08"N, 121°04'56"E 02.4.2000, leg. Freitag (310a)M"; 1 ♂, 3 ♀♀ (PNM, ZSM [FR088]) "PHIL.: Mindoro Oriental, Bongabong, Brgy. Formon, Pastuhan, Tangisan Falls; deep mountain valley, sec. forest, submerged wood, riffle, c. 200 m asl., c. 12°43'N, 121°23'E; 27.10.2011 leg. Freitag (318)M"; 11 L (0.22, 0.24, 0.25, 6 × 0.31, 2 × 0.32) (CFM) "PHIL: Or. Mindoro, Roxas, Brgy. San Vicente, Tauga River; rocks, riffle & run; sec.veget.; c. 12°37'18"N, 121°22'58"E, c. 140m asl; leg. Freitag 17.3.2012 (TR2g)M"; 1 ♂ [FR086] (ZSM), 4 L (0.21, 0.24, 0.29, 0.31) (CFM) "PHIL: Or. Mindoro, Roxas, Brgy. San Vicente, Tauga River; rocks, riffle & run; sec.veget.; c. 12°37'18"N, 121°22'58"E, c. 140m asl; leg. Freitag & Pangantihon 07.7.2012 (TR2g)M"; 3 ♂♂, 8 ♀♀ (SMTD) "PHIL: Or. Mind oro, Roxas, Brgy. San Vicente, Tauga River; subm. wood, run; sec.veget.; c. 12°37'18"N, 121°22'58"E, c. 140m asl; leg. Pangantihon, 22 Jan.2013 (TR2f)M"; 2 ♂♂, 2 ♀♀ (ZSM) "PHIL: Or. Mindoro, Roxas, Brgy. San Vicente, Sitio Tauga Diit, Baroc River tributary Tauga Diit; subm. wood, run & riffle; sec.veget.; 12°37'32"N, 121°21'17"E, 180m asl; leg. Freitag & Pangantihon, 05.Feb.2012 (TIRf)M"; 2 ♀♀ (CFM) "PHIL: Or. Mindoro, Roxas, Brgy. San Vicente, Baroc River tributary Hiyong Creek; side pool, lit toral sand and gravel; sec.veget.; c. 12°37'27"N, 121°22'48"E, 147m asl; leg. Freitag & Pangantihon, 05.Feb.2012 (THCe)M"; 6 L (0.22, 2 × 0.24, 0.27, 2 × 0.31) (NMW) "PHIL: Or. Mindoro, Roxas, Brgy. San Vicente, Baroc River tributary Hiyong Creek; subm. root packs, run; sec.veget.; c. 12°37'27"N, 121°22'48"E, 147m asl; leg. Freitag & Pangantihon, 07.Jul.2012 (THCh)M"; 3 ♂♂, 7 ♀♀, 3 L (0.27, 0.30, 0.31) (CFM) "PHIL: Or. Mindoro, Roxas, Brgy. San Vicente, Sitio Tauga Diit, Baroc River tributary Tauga Daka; subm. wood in run; sec.veget.; c. 12°37'56"N, 121°20'33"E, c. 350m asl; leg. Freitag, 4 Apr. 2013 (TDR2f)M"; 15 ♂♂, 14 ♀♀ (NMW) "PHIL: Or. Mindoro, Roxas, Brgy. San Vicente, Sitio Tauga Diit, Baroc River tributary Tauga Daka; subm. wood in run; sec.veget.; c. 12°38'05"N, 121°19'33"E, c. 530m asl; leg. Pangantihon, 18 Jan. 2013 (TDR3f)M"; 4 ♂♂, 7 ♀♀ (ZMUC) same locality and microhabitat "leg. Pangantihon, 23 Jan. 2013 (TDR3f)M"; 16 ♂♂, 14 ♀♀ (CFM) same locality and microhabitat "leg. Pangantihon, 15 Feb. 2013 (TDR3f)M"; 3 ♀♀, 2 L (0.27, 0.34) (PNM) "PHIL: Or. Mindoro, Roxas, Brgy. San Vicente, Sitio Tagaskan, Hinundugan River; rocks, run; sec.veget.; c. 12°35'22"N, 121°21'54"E, c. 200m asl; leg. Freitag & Pangantihon, 20.12.2011 (HR2g)M"; 4L (0.25 [FR090], 0.26, 2 × 0.31, 0.32) (ZSM): same locality and microhabitat "leg. Freitag & Pangantihon, 06.Feb.2012 (HR2g)M"; 2 ♂♂, 5 ♀♀ (CFM) "PHIL: Or. Mindoro, Roxas, Brgy. San Vicente, Sitio Tagaskan, Hinundungan River; subm. wood, run c. 12°36'30"N, 121°22'38"E, c. 200m asl; leg. Pangantihon; 31 Mar. 2013 (HR3f)M"; 6 ♂♂, 1 ♀, 9 L (2 × 0.24, 2 × 0.27, 3 × 0.30, 2 × 0.33) (CFM) "PHIL: Or. Mindoro, Roxas, Brgy. San Vicente, Sitio Tagaskan, Hinundungan River; rocks, riffle & run; c. 12°36'30"N, 121°22'38"E, c. 200m asl; leg. Freitag; 31 Mar. 2013 (HR3g)M"; 3 L (0.24, 0.25, 0.31) (CFM) "PHIL: Or. Mindoro, Roxas, Brgy. San Vicente, Sitio Quirao, Hinundugan tributary Quirao Buhay Creek; rocks, run; 12°36'10"N, 121°23'00"E, 130m asl; leg. Freitag & Pangantihon, 30.06.2012 (HBCg)M"; 1 L (0.30) (CFM) "PHIL: Or. Mindoro, Roxas, Brgy. San Vicente, Hinundugan tributary Tinggiwang Creek; subm. wood, run; 12°35'48"N, 121°22'00"E, c. 180m asl; leg. Freitag; 31 Mar.2013 (HTCf)M". Other material: 1 ♂ (CFM) "PHIL: Or. Mindoro, Roxas, Brgy. San Vicente, Tauga River; subm. wood, run; sec.veget.; c. 12°37'18"N, 121°22'58"E, c. 140m asl; leg. Freitag 28.Nov.2011 (TR2f)M".

Adult description.

Body 1.4-1.6 mm long (CL + exposed portions of head & tergit VIII); CL: 1.25-1.38 mm; CL/EW: 1.9-2.1. Colouration as in Fig. 4: entire dorsal head capsule, mouthparts, pronotum, and elytra (except for two pairs of yellow patches) black; anterior yellow elytral patches extending from humeri mediad approximately up to second row of elytral punctures, not reaching median elytral margin; posterior yellow elytral patches oval, not reaching median, lateral, and apical elytral margin; ventral side, coxae, trochanter, femur, proximal half of tibia, areas around tibial and tarsomere articulations, and claws brown; at least distal half of tibia and proximal portion of fifth tarsomere yellowish; antennae yellow (except for dark tips and basal segment).

Head (Figs 4, 13A) 0.33-0.36 mm wide (HW); ID 0.19-0.21 mm; labrum smooth, with moderately densely trichoid pubescence; clypeus (except for anterior margin) and frons with longitudinal striae on microreticulate ground, moderately densely covered with short trichoid setae; frontoclypeal suture straight and conspicuous. Eyes slightly protruding. Antennae (Fig. 13A) with 11 antennomeres, slender, slightly shorter than head width. Genae (Fig. 13A) reticulate, with indistinct pubescence. Gula (Fig. 13A) with regularly arranged, scale-like striae (including median portion), with inconspicuous pubscens; gular sutures absent. Mouthparts (Fig. 13A) almost as in Ancyronyx tamaraw except for shorter postmentum, that is rather sub-rectangular than trapezoidal; prementum with subapical row of eight very short trichoid setae; labial palps three-segmented, slightly longer then postmentum.

Pronotum (Fig. 7) 0.36-0.40 mm long (PL), 0.42-0.44 mm wide (MW), slightly wider than long (PL/MW), widest at about posterior 0.3, distinctly narrower than elytra, with deep transverse groove; anteriorly of transverse groove slightly vaulted; posterior portion broadly vaulted; posterolateral oblique grooves divided (two pairs), elongate, conspicuous; lateral margin distinctly arcuate; anterior margin distinctly convex; pronotal surface entirely microreticulate and rugose, with inconspicuous pubescence; lateral pronotal carina absent; hypomeron as pronotal surface. Prosternum (Fig. 13B) transverse, prosternal process broadly subpentagonal, distinctly wider than long, both appearing rugose by microreticulation superimposed with irregularly shaped setiferous tubercles.

Metascutellum subcordiform, micropunctate. Elytra (Fig. 4) broadly elongate, 0.89-0.98 mm long (EL), 0.61-0.66 mm wide (EW), c. 1.4-1.5 times as long as wide (EL/EW), almost parallel-sided in anterior 0.1-0.65, anteriorly slightly convergentposteriorly roundly convergent to apices, with c. nine longitudinal, moderately impressed rows of punctures (counted at level of metacoxae); median rows rather inconspicuous; lateral rows more regular and more deeply impressed than median rows; six to seven strial rows between suture and humerus; punctures moderately large and moderately deeply impressed, lateral punctures deeper than median ones; interstices and intervals granulose to micropunctate; lateral elytral gutter narrow; humeri roundly obtuse; elytral apices inconspicuously separately rounded.

Mesoventrite (Fig. 13B) very short, most anteriorly micropunctuate, posteriorly granulose, with deeply impressed median longitudinal impression. Metaventrite (Fig. 13B) large, without glabrous areas, entirely microreticulate superimposed with irregularly shaped setiferous tubercles; the latter appearing reticulately connected in lateral portions; tubercles smaller and shallower at disc; median longitudinal impression deeply impressed, laterally extending into a subtriangular groove; groove without setiferous tubercles. Anepisternum 3 microreticulate with one row of punctures. Hind wings present in all specimens examined, venation not examined.

Legs (Figs 4, 13B, J) approximately as long as body, or very little shorter; coxae large, only procoxae visible in dorsal view; pro- and mesocoxae (Fig. 13B) subglobular (drop-shaped); metacoxae (Fig. 13B) rather obtuse and shallowly elevated, obliquely conoidal; trochanter (Fig. 13B) short, broadly lanceolate, not visible in dorsal view, distal end distinctly pointed; femora and tibiae appearing longitudinally striated by dense cover with very elongate, micro-setiferous tubercles; tibiae distally with rather short and inconspicuous setae; tarsomeres with small scattered setae (Fig. 13J), most conspicuous at ventral side and near claw insertation; claws (Fig. 13J) large, rather slender, strongly bent; base of each with three teeth, distal one very large (mutilated in specimen figured in 13J).

Ventrite 1 (Fig. 13B) arcuately projected anteriad between hind coxae; microreticulate and tuberceliferous as in metaventrite especially near anterior margin. Ventrites 2 -4 (Fig. 13B) with evenly distributed, subcordiform, setiferous tubercles; interstices almost glabrous; ventrite 5 (Figs 13C, D) evenly covered with short adpressed setae emerging from subcordiform tubercles; lateral projection shallow.

Sternite IX (Figs 13G, H) c. 340 µm long, with moderately long anterior strut (distal end broken off in specimen figured in 13G), apical corners rounded, each with one lateroapical seta and one inconspicuous sublateroapical seta; apical margin slightly broadly emarginate; longer paraproct almost reaching apical margin.

Aedeagus (Figs 13 K–N) similar to that of Ancyronyx minutulus (see Freitag and Jäch 2007: figs 15a, b), but distinctly larger (c. 350 μm long), relatively stouter and without long setae. Median lobe moderately long and moderately slender, with few indistinct pores, subapically straight, not widened, c. 90 μm wide, apically distinctly curved ventrad (lateral view, Figs 13M, N); tip rounded; ventral sac weakly sclerotised except for lateral rim (Figs 13K, M); fibula weakly sclerotised, inconspicuous in transillumination; corona inconspicuous. Phallobase asymmetrical, bent lateroventrad, distinctly longer ventrally, with conspicuous, strongly sclerotised margins; basolateral (penile) apophyses inconspicuous; ejaculatory duct well scleotised and conspicuous in transillumination. Parameres elongately subtriangular, rather short, reaching about basal 0.67 of aedeagus, almost contiguous ventrally, subapically slightly widened ventrad; apices with one apical and one subapical very short setae (Figs 13K, M); basal margin oblique and not conspicuously emarginate (lateral view, Figs 13M, N).

Ovipositor (Fig. 13O, P) c. 410 µm long. Stylus slender, rather staight, with various apical sensilla. Coxite moderately stout, distinctly shorter than in specimens of the Ancyronyx patrolus species group, but longer than in those of the Ancyronyx variegates group; outer margin concave; all over with several rather short and broad, peg-like spines, increasing in size and density apically at lateral margins; inner margin pubescent; basal portion short. Valvifer moderately longer than coxite; fibula slightly curved.

Secondary sexual characters: Sternite VIII in male short, weakly sclerotised and with very short median strut; in female (Fig. 13I) distinctly longer, more sclerotised than in male medially emarginate; apical corners rounded and with small seate; median portion with dense micro-pubescence. Tergite VIII in female (Fig. 13E) subtriangular, almost as long as wide (c. 210 µm long, 230 µm wide), with few moderately short setae; condyles large and conspicuous. Tergite VIII in male (Fig. 13F) subsemicircular, distinctly wider than long (c. 170 µm long, 230 µm wide), shorter than in female, reticulate; apical half with moderately short setae. Ventrite 5 in female (Fig. 13C) subtriangular (c. 230 µm long, 400 µm wide); in male (Fig. 13D) broadly oval and distinctly shorter (c. 180 µm long, 370 µm wide).

Adult differential diagnosis.

In its colour patterns, Ancyronyx buhid resembles Ancyronyx patrolus , Ancyronyx punkti and especially Ancyronyx pseudopatrolus from Palawan. The new species can be easily distinguished by the combination of body morphometric and genital characters (body, especially abdomen and elytra, relatively wider (CL/EW c. 2.0; EL/EW c. 1.45) than in other species; legs not distinctly longer than body; coxite of ovipositor moderately stout; aedeagus with straight main piece (not widened subapically), almost contiguous parameres ventrally, very short and few parameral setae.

Larval diagnosis

(based on sixth instar). Colour (Fig. 7) dorsally dominantly dark brown except for yellow lateral head, clypeus and labrum, most anterior portion of pronotum and the almost entire first abdominal segment; most specimens additionally with yellowish to pale brown (preterminal) abdominal segment VIII (at least posterior portion) and apex of abdominal segment IX (up to c. posterior 0.15). Legs, mouthparts, ventral head, thorax, and abdomen yellowish to pale brown, but some specimens with darker brown thoracic venter and ventral abdominal segment IX.

HW 0.31 mm; entire larva about 3.1 mm long. Body elongate, wider than that of Ancyronyx minerva and Ancyronyx tamaraw , but similar in the external characters, except for the following: posterolateral projections (Figs 7, 14A) of abdominal segments II–VI usually reaching or slightly overreaching posterior segment margins. Lateral rim of thorax and abdomen with scattered long, trichoid setae. Dorsal sagittal line slightly impressed from prothorax to abdominal segment V and without tubercles.

Head (Figs 7, 14 B–E) widest posterior 0.3, not subparallel in posterior half, dorsolaterally with a pair of moderately long setae and one pair near the frontoclypeal suture (Fig. 14B); lateral setae of various size, very short to moderately long. Frontal suture inconspicuous; subbasal fringe of clypeus with rather short fasciculate setae. Ventral side (Fig. 14D) dominantly rugulose; basolateral areas and genae (inbetween setae) glabrous (Fig. 14C).

Antenna as in Figs 14D, E, c. ¼ as long as head; scape setae fasciculate; pedicel long; flagellum and sensorium subequal in length.

Labrum (Fig. 14B) with subapical fringe of ramose setae and few lateral trichoid setae. Maxilla (Fig. 14D) with parallel-sided stipes; maxillary palpus (Figs 14D, E) slightly slenderer than in Ancyronyx tamaraw . Labial mentum (Fig. 14D) with lateral margin slightly sinuously curved (concave in posterior half), narrowest at basal 0.2; pair of trichoid setae moderately short (reaching anterior margin), inserted sublaterally at anterior 0.2; pair of subapical lateral setae fasciculate; subbasal pair of setae ramous. Submentum short, not clearly partitioned from somewhat protruding semicircular ligula which is conspicuously covered with setiform microstructures (Fig. 14D); labial palpi as in Ancyronyx tamaraw .

Pro-, meso-, metathorax and legs (Figs 7, 14F) almost as in Ancyronyx minerva . Pronotum with rather inconspicuous small round signa (glabrous areas) in posterior half. Ventral sclerites of thorax (Fig. 14E) rugulose, not glabrous; venter of metathorax with conspicuous sagittal tuberculate ridge (similar to that of the venter in abdominal segment I).

Abdomen (Figs 7, 14A, H, I) without conspicuous dorsosagittal carina except for the anterior half of segment IX (Fig. 12G); squamose setae at posterior rim of segments I–VIII large (Figs 14A, H). Ventral sclerite of segment I with distinct sagittal ridge in anterior half (Fig. 14F), reaching c. 1/2 to 2/3 of segment length. Apex of segment IX emarginate (sometimes inconspicuous due to apical setae). Operculum (Fig. 14I) almost twice as long as wide, basal portion glabrous.

Variation between larval instars.

The available prefinal instar specimens vary only slightly from the description above, namely by the relatively slenderer thoracic and abdominal segments, the smaller and rather inconspicuous spiracles near the posterolateral projection, the slightly broader legs with fewer setae, and the relatively longer lateral setae on thorax and abdomen.

Larval differential diagnosis.

The species can most easily be distinguished from any other known Ancyronyx larva by the obviously pale first abdominal segment. The general shape and the proportions of the larva of this species resemble those of the Ancyronyx patrolus group, from which it can be additionally distinguished by the anterior yellow band, that is medially narrower (not extended as in several species of the Ancyronyx patrolus group) and the character combination of long sagittal crest of the first abdominal segment venter, slightly impressed dorsosagittal line without protruding tubercles. From the species of the Ancyronyx variegatus group, this larva can be distinguished easily by its spindle-shape habitus (subsemicircular in cross section) and the rather short posterolateral appendages.

Distribution.

Known only from Mindoro Island where this new species was recorded from various streams in the province of Oriental Mindoro.

Ecology.

Both, adult and larvae of Ancyronyx buhid occur in medium sized, unpolluted rivers in mountainous areas. This suggests an affinity to undisturbed habitats. The relatively highest abundances were found on submerged wood and rough rock surfaces in runs and riffles. Some root packs and partly submerged grass bunches in riffles were also found to be densely colonised with the species. Much more rarely it was found among bottom gravels in runs and calm pools, where specimens were possibly just shifted by drift.

Remarks.

One male specimen from site “TR2f” varies in regard to the primary and secondary sexual characters, namely the length of tergite VIII, ventrite 5 and aedeagus. Since all other characters do not differ from the type material, this is regarded as an abnormality caused during pupation.