Two new species of Anacaena Thomson, 1859 (Coleoptera, Hydrophilidae) from Northern Luzon, Philippines Author Sanchez, Enrico Gerard S. Ateneo Biodiversity Research Laboratory, Department of Biology, School of Science and Engineering, Ateneo de Manila University, Quezon City, 1108 Philippines enrico.sanchez@obf.ateneo.edu Author Delocado, Emmanuel D. https://orcid.org/0000-0001-7731-3476 Ateneo Biodiversity Research Laboratory, Department of Biology, School of Science and Engineering, Ateneo de Manila University, Quezon City, 1108 Philippines Author Freitag, Hendrik https://orcid.org/0000-0002-1325-0979 Ateneo Biodiversity Research Laboratory, Department of Biology, School of Science and Engineering, Ateneo de Manila University, Quezon City, 1108 Philippines text ZooKeys 2022 2022-07-12 1112 11 25 http://dx.doi.org/10.3897/zookeys.1112.85752 journal article http://dx.doi.org/10.3897/zookeys.1112.85752 1313-2970-1112-11 F9F1E9A2CB9249CB8D4CFB3FAC592F96 59936DE5F02E5E1D8346772863977AEA Anacaena auxilium sp. nov. Figs 3-4 , 6 Type locality. Philippines • Luzon, Mountain Province, Bauko; Besang mountain river, Chico River tributary; rural/agricultural area; boulders; 17°00'14"N , 120°53'49"E ; ca. 1080 m a.s.l. Type material. Holotype : Philippines • ♂ (PNM: GS066), "PHIL.: Luzon, Mountain Province, \ Bauko; Besang mt. river, Chico River tributary; \ rural/agricultural area; boulders, \ 17°00'14"N ; 120°53'49"E ; ca. 1080 m a.s.l.; \ Nov. 1997, leg. Mey (451)L"; GS066, specimen and terminal parts of the abdomen, including genitalia, were glued separately on the entomological card. Paratypes : Philippines • 1♂, 2♀♀ (ADMU: GS009, GS067; ZMB: GS010): same data as holotype. • 1♂, 2♀♀ (ADMU: GS034, GS035, GS038): Luzon, Ilocos Sur, Suyo Municipality, Tagudin-Cervantes-Sabangan Road, Besang Pass Area; secondary forest, mountain creek; 16°57'17"N ; 120°38'57"E ; ca. 1200 m a.s.l.; 15 Apr. 2019, leg. Freitag, Garces, Pangantihon "(448)L" . Description. (Fig. 3 ). TL 2.8 mm (2.3-2.8 mm); TW 1.7 mm (1.4-1.7 mm); EL 1.8 mm (1.5-1.9 mm). Body form oval, moderately convex (Fig. 4 ); elytra about 3.4 times as long as pronotum (dorsal view), greatest width at anterior one-third. Head : Clypeus black, moderately large, straight anteriorly, with distinct antero-lateral angle. Frons black; frontoclypeal suture visible laterally. Labrum black. Puncturation regular, coarse, shallowly impressed; interstices as wide as diameter of one puncture mediad, approximately twice as wide as diameter of punctures laterad; series of densely arranged punctures along inner margin of eyes absent. Ventral punctures obsolete. Maxillary palpomeres yellow to brown; palpomeres 1-3 dark yellow; palpomere 2 moderately inflated. Palpomere 4 almost entirely infuscated, lighter towards palpomere 3, widest towards mid-length; inner margin slightly convex; outer margin distinctly convex. Mentum with fine setae on lateral margins; anterior margin with median incision. Labial palpi stout, not longer than lateral edge of mentum; palpomere 3 slightly longer than palpomere 2. Eyes not constricted anteriorly, dorsal and ventral portions of almost equal size. Antennae capitate, 9-segmented; scape parallel-sided; pedicel narrowest towards mid-length; antennomere 1 (segment 3) not distinctly elongated, broadest at base, narrows distally; antennomeres 2-4 smallest in length and width, lighter than adjacent segments, smaller than antennomere 1 (segment 3), increasing size distally; antennomere 5-7 darkest of all antennomeres; antennomeres 5 and 6 of equal length; setae along lateral margins black, long, thick, erect. Segment 7 irregularly shaped, asymmetrical; segment 8 globular. Terminal segment as long as segments 7 and 8, widest at base, subparallel on lateral margins, asymmetrical apicad with apex present on distal side; setae distributed throughout, black, long, thick, erect, but setae on apical one-third longer. Preocular patches absent. Thorax : PW/PL = 2.62; PL/PW = 0.38. Pronotum largely black, with narrow light brown or yellow lateral margins not wider than diameter of eye. Puncturation of two series: larger, coarser series evenly spaced, with interstices as wide as diameter of one puncture; smaller, fine series near postero-medial margin, irregularly scattered, one-fourth as wide as larger series. Anterior margin curving inwards on both sides from antero-lateral angle, with deepest point on 0.2 laterad and curving outwards mediad. Lateral margins slightly curved, without setae. Postero-lateral angle ca. 70-80°. Posterior margin almost straight with curvature laterad. Prosternum flat. EL/EW = 1.13; EL/PL = 4.13; EW/PW = 1.11; TL/EW = 1.69. Elytra black, with very narrow brown lateral margins and posterior area; setae absent. Shoulder regions not accentuated. Punctures coarse, strongly impressed especially near the disc, arrangement dense, spacing as wide as punctures near the disc, wider than punctures laterad; depressions or rows of coarser punctures on lateral portion absent. Mesoventrite distinctly elevated medially, with slightly pointed protuberance. Legs : Dark brown, but tarsi lighter. Spine-like setae on procoxa present. Metafemur pubescent on proximal one-fourth and near outer margin, hairline direction horizontal and recumbent. Tibia with long, thick, black, spine-like setae along lateral margins, pointing distally; terminal pair of setae at least 1.5 times as long as adjacent setae; tibiae length ratio (protibia: mesotibia: metatibia) 1: 1.3: 1.5. Metatarsus size as long as metatibia or slightly shorter. Tarsi length ratio (protarsus: mesotarsus: metatarsus) 1.0: 1.4: 2.2. Aedeagus : (Fig. 6 ) Parameres apical region blunt, broadly pointing medially, slightly asymmetrical; inner margins almost straight on anterior half, widening medially on posterior half, mesal gap tapering to a narrow opening about 0.25 times as long as parameres; outer margins convex, bulging at anterior 0.5; combined width of parameres approximately the same or slightly broader as diameter of phallobase; basal portion 4 times as wide as apical part. Median lobe with apex blunt, apical portion subparallel, broadening starting in anterior 0.25, broadest before basal apophyses; base of median lobe not distinctly connected with parameres, about 2 times as wide as the width of the apex of median lobe; basal apophyses barely extending beyond the anterior portion of phallobase, narrow and subparallel. Phallobase longer than parameres, longer than wide; median reinforcement or pigmented line absent. Differential diagnosis. A. auxilium sp. nov. (Fig. 3 ) is remarkably larger than most Philippine congeners. In length, A. auxilium sp. nov. (2.3-2.8 mm) overlaps with A. cordillera Komarek & Freitag, 2014 (2.6-3.1 mm) and A. levistriata Komarek & Freitag, 2014 (2.1-2.7 mm). However, the new species has a smaller body width than A. cordillera (1.3 mm vs.> 1.5-1.8 mm) and a longer elytral length (1.5 mm vs. <1.20-1.27 mm) than both congeners. Additionally, the new species has stout labial palpi which are not longer than the lateral edge of the mentum, while both A. cordillera and A. levistriata have labial palpi longer than the lateral edge of the mentum. Additionally, the labial palpi of A. auxilium sp. nov. are stout, while the labial palpi of A. cordillera are slender. Moreover, pre-ocular patches are absent in A. auxilium sp. nov., while these are distinct in A. cordillera . Remarkably, the new species has a bi-punctuate elytra with large, coarse series and small, fine series, while A. cordillera only exhibits the latter and A. levistriata only exhibits the former. While the parameres of the new species and A. levistriata look similar, A. auxilium sp. nov. can be differentiated in that its median lobe is distinctly longer (ca. 0.4 x ) than its parameres. Meanwhile, the apical portions of the median lobe and parameres of A. cordillera are clearly different from those of the new species. Distribution. The species is documented from two nearby localities, namely Ilocos Sur and Mountain Province (Fig. 7 ). Remarks. Specimens from a preserved collection during 1997 fieldwork showed no pertinent phenotypic plasticity to specimens collected in a field expedition 22 years later. No external sexual dimorphism is observed. Etymology. The species epithet 'auxilium' is Latin for 'help' . The new species is dedicated to the Mary Help of Christians Seminary system to which the first author expresses gratitude for constant inspiration. Additionally, 'help' alludes to the vulnerable state of freshwater biodiversity in the tropics.