Buchnerillo atlanticus sp. nov., a new halophilic woodlouse (Isopoda: Oniscidea: incertae sedis) from the Atlantic coast of the Iberian Peninsula, with ecological remarks Author Garcia, Lluc 914965A1-6DEB-4870-94A3-B4E41B018921 Balearic Museum of Natural Sciences - Interdisciplinary Ecology Group, University of Balearic Islands, Mallorca, Spain. llucgarciaisopoda@gmail.com Author Robla, Jairo 9FBE706B-F463-4CA7-9AC9-BEF1B6FB8689 Department of Conservation Biology, Doñana Biological Station - CSIC, Sevilla, Spain. jairoroblasuarez@gmail.com text European Journal of Taxonomy 2022 2022-05-23 821 1 15 journal article 56754 10.5852/ejt.2022.821.1793 832320f4-ad13-4df5-af31-15dd1da92bf2 2118-9773 6580741 2D78A872-DD3B-4D15-81CA-50BEA8E57821 Buchnerillo atlanticus sp. nov. urn:lsid:zoobank.org:act: 39D99F57-E621-4F96-99EC-95AE7F48D45C Figs 2–7 Diagnosis Species of Buchnerillo characterized by ovoid and endoantennal conglobation type . Cephalon, pereontergites and pleon-tergites smooth and covered with long setae regularly arranged. Frontal area striated, not grooved. Mandibles with dichotomized molar penicil. First pereon-tergite posterolateral corner without schisma. Endopod of male pleopod 1 with straight distal part. Etymology The name of the species comes from the Atlantic Ocean (concretely the Cantabrian Sea) which is the area where the specimens were collected. Material examined Holotype SPAIN • ♂ ; Principality of Asturias , Villaviciosa , Selorio (Conejera beach); 43º31′56.1″ N , 5º21′48.3″ W ; 3 m a.s.l. ; 3 Sep. 2021 ; J. Robla leg.; hand collected from the lower face of embedded stones ; MNCN 20.04/14403 . Paratypes SPAIN • 3 ♀♀ ; same collection data as for holotype; MNCN 20.04/14404 to 20.04/14406 • 1 ♀ ; same collection data as for holotype; 9 Jul. 2021 ; MNCN 20.04/14407 • 10 specs; same collection data as for holotype; 13 Jul. 2021 ; MNCN 20.04/14408 to 20.04/14417 (both included) • 1 ♂ (specimen mounted in 3 microscope slides); same collection data as for holotype; 1 Jul. 2021 ; MBCN 24683-1 to 24683-3 • 1 ♀ ; same collection data as for holotype; 9 Jul. 2021 ; MBCN 23149 . Additional material SPAIN • 1 ♀ (specimen used for SEM); same collection data as for holotype; 1 Jul. 2021 ; CLLG . Description MEASUREMENTS. Maximum length observed: male 1.7 mm , female 3.2 mm . COLOUR. Cephalon and epimera pale. Rest of body reddish or yellow-orange with darker irregular reticulated spots, with slight variability ( Figs 2A–B , 3D ). BODY. Conglobation ovoid, endoantennal ( Figs 2C , 3A ). Surface of body without prominent tubercles; cephalon and tergites regularly covered with erected and long setae ( Figs 2A–B , 3A–B ) as follows: five rows of setae on cephalon and pereon-tergite 1; two rows on posterior half of pereon-tergites 2–7 and pleon; one row on pleotelson; setae emerge from cuticular pits ( Fig. 3C ). Fig. 2. A–B . Alive specimens of Buchnerillo atlanticus sp. nov. in their habitat (photo: N. Noval). C . Buchnerillo atlanticus sp. nov. conglobated after suffering a disturbance (photo: M. Álvarez Fidalgo). Fig. 3. Buchnerillo atlanticus sp. nov. , ♀ (CLLG). A . Whole animal, partially conglobated. B . Last pereonites, pleon and pleotelson, lateral view. C . Tergal setae. D . Short time preserved specimen in lateral view. Scale bars: A, D = 0.5 mm; B = 0.3 mm; C = 0.015 mm. CEPHALON. With frontal and suprantennal ridges, delimiting frontal shield; upper margin regularly curved; lower margins concave, delimiting on each side hollows in which antennae are housed during conglobation ( Fig. 3A ). Frontal shield surface covered with fine transverse striae ( Fig. 3A ). Eyes formed by one ocular spot, not well-defined as ommatidium. PEREON. Pereon-tergite 1 with anterolateral margin rounded and protruded; posterolateral margin without schisma; with short ventral lobe ( Fig. 4A ); hind margin straight. Pereon-tergites 2–4 with slightly sinuous hind margin; epimera subtriangular, with rounded lateral margins. Pereon-tergites 3–7 with quadrangular epimera. PLEON. Pleon-tergites 1–2 not visible. Epimera of pleon-tergite 3 not visible. Pleon-tergites 4–5 with straight lateral margin ( Fig. 3B ). PLEOTELSON. Twice wider than long, with curved anterior edge, converging sides, and straight hind margin ( Fig. 3A ). FIRST ANTENNA. Two articles; first article slightly longer than second; second article with two long apical aesthetascs ( Fig. 4B ). Fig. 4. Buchnerillo atlanticus sp. nov. , paratype, ♂ (MBCN 24683). A . Left half of pereon-tergite 1, extended; the interrupted lines represent the ventral lobe. B . First antenna. C . Second antenna. Figure not to scale. Fig. 5. Buchnerillo atlanticus sp. nov. , paratype, ♂ (MBCN 24683). A . Distal part of maxilliped. B . Maxilla. C . Maxillula, outher branch. D . Maxillula, inner branch. E . Left mandible. F . Right mandible. Figure not to scale. Fig. 6. Buchnerillo atlanticus sp. nov. , paratype, ♂ (MBCN 24683). A . Pleotelson and uropods, ventral view. B . First pereopod; arrow indicates divided setae of carpus and pectinate scale of propodus. C . Seventh pereopod. D . First pleopod. E . Second pleopod. F . Genital papilla. Figure not to scale. SECOND ANTENNA. Thick and short, with long setae on peduncular articles; flagellum with three articles; two aesthetascs on second flagellar article ( Fig. 4C ). MOUTHPARTS. Maxilliped: endite narrow, as long as 3/4 of palp length, with one thin apical penicillium; palp with two strong setae on basal article and one on distal article ( Fig. 5A ). Maxilla distally rounded, bearing about 10 tubular setae ( Fig. 5B ). Maxillula: inner branch distally pointed, without penicils ( Fig. 5D ); outer branch with 5+ 4 apically entire teeth and one supplementary seta among outer group ( Fig. 5C ). Left mandible with dichotomized molar penicil, with 2+1 free penicils ( Fig. 5E ); right mandible with dichotomized molar penicil, with 1 +1 free penicils and toothed lacinia mobilis ( Fig. 5F ). PEREOPODS. Short, with one long divided seta on carpus. Dactylus with long and plumose dactylar seta. PLEOPODS. All exopodites without pleopodal lungs. UROPODS. Endopod twice as long as exopod, both with long apical setae ( Fig. 6A ). Male Pereopods 1 and 7 without distinct modifications ( Fig. 6B–C ). First pleopod with exopod small, reniform, without setae; endopod with very wide basal part and narrow, almost straight, distal third ( Fig. 6D ). Second pleopod: exopod elongated-ovoid, with marginal hairs and two subdistal setae; endopod with long and thin distal half ( Fig. 6E ). Genital papilla as in Figure 6F . Remarks Buchnerillo atlanticus sp. nov. is distinguished from the other three known species of the genus, in addition to other morphological characteristics, by the lack of dorsal tubercles and by having long sensory setae. According to the respective original descriptions, it also differs from the other species by having the mandibles with dichotomized molar penicil, instead of semi-dichotomized. In addition to these morphological features, it is distinguished from B. litoralis by its ovoid rather than spherical conglobation ( Vandel 1960a ), by the shape of the endopod of the first male pleopod, which in B. atlanticus is almost straight with a very wide basal part and in B. litoralis has a curved distal part, apically dilated ( Vandel 1960a ). Both species have the frontal area of the cephalon not excavated, but covered with fine transverse striae. In addition to the characteristics already mentioned, B. atlanticus is distinguished from B. oceanicus by the cephalic structure, with striated instead of grooved frontal area ( Ferrara 1974 ). Buchnerillo atlanticus , B. litoralis and B. oceanicus share the lack of schisma in the first pereontergite and presence of a short lobe in its ventral part. Finally, B. atlanticus is also distinguished from B. neotropicalis by the absence of schisma in the first pereon-tergite and by the shape of the male first pleopods, among other characteristics ( Taiti et al. 2018 ). The most distinctive morphological features of the four known species of Buchnerillo are presented in Table 1 . Distribution Buchnerillo atlanticus sp. nov. is only known from its type locality of Conejera beach in Villaviciosa ( Asturias , Spain ) ( Fig. 1A–B ).Although several localities with similar ecological conditions were visited, no specimens were found. Up to date, each species of Buchnerillo belong to different coastal areas of the world: Buchnerillo litoralis occurs on the Mediterranean shores, B. oceanicus on the coasts of the Indian Ocean, B. neotropicalis on the coasts of the Pacific Ocean and B. atlanticus on the Cantabric coast of the Atlantic Ocean ( Fig. 7 ). Ecology Buchnerillo atlanticus sp. nov. was always found in Conejera beach areas with fine-grained sand. All the specimens were adherent to the lower face of large highly humid stones embedded in the substrate. Contrary to the habitat of other species of Buchnerillo , in the study area no logs or plants remains are present ( Fig. 1B ). Several specimens seemed to be seen feeding on small patches of algae and other organic material adhered to the rocks. Apparently, the presence of B. atlanticus was not altered by frequent survey and handling of the same stones in the short sampling period. Buchnerillo shared habitat with three other halophilic woodlice: Armadilloniscus candidus Budde-Lund, 1885 , Halophiloscia couchii (Kinahan, 1859) and Ligia oceanica (Linnaeus, 1767) . Buchnerillo atlanticus did not present particular conspecific aggregations. Other arthropods present in the area were the pseudoscorpion Neobisium maritimum Leach, 1817 and the chilopod Geophilus easoni Arthur et al., 2001 both potential predators of B. atlanticus . Several species of halophilic Collembola, staphylinid Coleoptera and tiny mites were also present in the study area, in addition to some other accidental arthropod taxa from the cliff. Regarding its behaviour, it was always seen moving slowly among the organic material and small grains of sand stuck to the lower face of the stone ( Fig. 2A–B ). In case of disturbance the individuals rolled into an ovoid ball that remained adhered to the surface due to the humidity ( Fig.2C ). The shape and colour of Buchnerillo provides this woodlouse with an almost perfect camouflage, looking like one more sand grain in the microhabitat under the stone ( Fig. 2A ). In case of a major or continuous disturbance it ended up opening slightly and releasing itself from the stone, falling to the substrate where they turn complete untraceable. The specimens showed some photophobic behaviour (Supplemental material). When the stones were lifted, B. atlanticus moved into the shade. This species is thought to be very sensible to dehydration. When specimens were removed from their habitat it only took a few minutes to die. Buchnerillo atlanticus needs constant humidity, present in its habitat under stones embedded in humid substrate. Its habitat is subject to tidal influence with occasional submersion. Specimens of B. atlanticus were seen between July and September, with a slightly variation in population abundance among consecutive days.