Ventral Tube Research Articles

Smooth post-labial chaetae in Homidia (Collembola, Entomobryidae) and the description of four new species from China with the aid of DNA barcoding.

Four new species of Homidia are described from the Guangxi Zhuang Autonomous Region, China. Homidialongiantenna sp. nov. is characterised by its long antenna and slightly expanded post-labial chaetae; H.guangxiensis sp. nov. by the presence of smooth chaetae on the post-labium and posterior face of the ventral tube; H.huapingensis sp. nov. by the presence of smooth post-labial chaetae and pointed tenent hairs; and H.oligoseta sp. nov. by the pointed tenent hairs and fewer macrochaetae on Abdomen IV. Additions to the original description of Homidiaacutus Jing & Ma, 2022 are also provided.

The functional evolution of collembolan Ubx on the regulation of abdominal appendage formation.

Folsomia candida is a tiny soil-living arthropod belonging to the Collembola, which is an outgroup to Insecta. It resembles insects as having a pair of antennae and three pairs of thorax legs, while it also possesses three abdominal appendages: a ventral tube located in the first abdominal segment (A1), a retinaculum in A3, and a furca in A4. Collembolan Ubx and AbdA specify abdominal appendages, but they are unable to repress appendage marker gene Dll. The genetic basis of collembolan appendage formation and the mechanisms by which Ubx and AbdA regulate Dll transcription and appendage development remains unknown. In this study, we analysed the developmental transcriptomes of F. candida and identified candidate appendage formation genes, including Ubx (FcUbx). The expression data revealed the dominance of Dll over Ubx during the embryonic 3.5 and 4.5days, suggesting that Ubx is deficient in suppressing Dll at early appendage formation stages. Furthermore, via electrophoretic mobility shift assays and dual luciferase assays, we found that the binding and repression capacity of FcUbx on Drosophila Dll resembles those of the longest isoform of Drosophila Ubx (DmUbx_Ib), while the regulatory mechanism of the C-terminus of FcUbx on Dll repression is similar to that of the crustacean Artemia franciscana Ubx (AfUbx), demonstrating that the function of collembolan Ubx is intermediate between that of Insecta and Crustacea. In summary, our study provides novel insights into collembolan appendage formation and sheds light on the functional evolution of Ubx. Additionally, we propose a model that collembolan Ubx regulates abdominal segments in a context-specific manner.

A new canopy-dwelling species of the genus Alloscopus Brner (Collembola: Orchesellidae: Heteromurinae) from Mt. Makiling, Philippines.

A new species of Alloscopus Brner, 1906 (Orchesellidae: Heteromurinae), A. arborealis sp. nov., is herein described from Mt. Makiling, Laguna, Philippines. The new species is distinct from its blind congeners by the combination of: 7+7 macrochaetae on head An series and 1+1 on M series; 13+13 macrochaetae on thorax II (vs. 912) and 7+7 central on thorax III (vs. 6+6); absence of the microsensilla on abdomen I; abdomen IV with four sensilla (vs. three); and ventral tube with a small number of chaetae on its posterior face (45 vs. 1123) and lateral flap (7 vs. 916). The complete body chaetotaxic pattern of the new species and a revised key to the world fauna of Alloscopus are also provided.

Two new species of Sminthurididae (Hexapoda, Collembola, Symphypleona) from Brazil with notes on Denisiella Folsom & Mills and Sphaeridia Linnaniemi.

Two new species of Sminthurididae, Sphaeridiapiauiensis Medeiros & Bellini, sp. nov. and Denisiellapiracurucaensis Silva, Medeiros & Bellini, sp. nov. from Piaui state, Brazil, are herein described and illustrated. Sphaeridiapiauiensissp. nov. resembles species of the irmleri group, like S.irmleri Bretfeld & Gauer, S.fibulifera Bretfeld & Gauer, and S.peruensis Bretfeld & Schulz, by its complex male ventral tube without asymmetrical structures or medial process. However, it differs from them by the combination of the male tibiotarsus III with a leaf-shaped IIpe chaeta and a regular IIIpi chaeta, ventral tube with 1+1 chaetae, and the absence cuticular hooks on the furca. Denisiellapiracurucaensissp. nov. resembles its congeners without the nasal organ, especially D.colombiana Ospina & Palacios-Vargas, by the presence of spiniform chaetae at least on the second antennal segment of the females, four serrated spines on tibiotarsus III, and the ventral dens chaetotaxy, but D.piracurucaensissp. nov. differs from the latter especially by the presence of 8+8 eyes and the shape of the male proximal tibiotarsal organ. To describe both species all Neotropical Sphaeridia and all described Denisiella species were surveyed, presenting notes on both genera, comparative tables, and keys for these taxa.

Intraductal papillary mucinous neoplasm of the accessory pancreatic duct in the pancreas uncinate process: A case report.

Intraductal papillary mucinous neoplasms (IPMN) of the accessory pancreatic duct (APD) are very rare and their clinical significance is not known. Here, we describe a case of IPMN originating in a branch of the duct of APD within the uncinate process of the pancreas, which initially presented with acute pancreatitis. A 70-year-old man visited our medical center presenting with acute pancreatitis around the head and uncinate process of the pancreas. Computer tomography scans revealed the presence of a 35-mm cystic mass-like lesion within the pancreas uncinate process communicating with a branch of the APD. The patient was diagnosed with APD-IPMN in the pancreas uncinate process accompanied by acute pancreatitis. Conservative management of the acute pancreatitis relieved his symptoms, while duodenum-preserving partial pancreatic head resection (DPPHR-P) was performed to treat the APD-IPMN. Intraoperative exploration showed the presence of severe adhesions within the uncinate process of the pancreas and that the tumor's "peduncle" - a branch of the duct of APD - was saddling just at the front of the main pancreatic ducts. Thus, surgical removal of the tumor required special handling of the region between the main duct (MD) and APD to protect the integrity of the main pancreatic ducts. Finally, a 35*30*15 mm IPMN was successfully removed and the MD was preserved combined with ligation from the root of the APD of the pancreas. The drainage volume of the ventral tube increased by around 20-fold in 24 hours on the fourth day after surgery. The presence of high amylase levels in the drainage discharge (40713.5 U/L) led to the diagnosis of postoperative pancreatic fistula (POPF). The drainage volume remained high for 3 days. The patient was discharged and POPF was successfully managed through endoscopic pancreatic duct stenting. APD-IPMN in the pancreas uncinate process has its own characteristics of localized pancreatitis, and MD-preserving DPPHR-P not only protects the exocrine and endocrine functions of the pancreas, but it also protects the physiological and anatomical integrity. The appearance of POPF after DPPHR-P may be managed by endoscopic pancreatic duct stenting.

A revision of the genus Isotomurus (Collembola: Isotomidae) in northern Iran using molecular evidence

Three new species of Isotomurus Börner are described from northern Iran. Status of studied populations is confirmed as new species by using COI and 28SrRNA markers. The new species belong to species-group characterized by 3,3,1 trichobothria on Abd. II-IV, 3+3 laterodistal setae on ventral tube, and no seta on mucro. Isotomurus hyrcanicus sp. nov. is similar to I. palustris Müller in color pattern, but has two lateral bands on last abdominal segments and 10-13 setae on retinaculum. Results of COI analyses shows that all color forms in population of the new species are conspecific. Isotomurus potapovi sp. nov. has a dorsomedial band from Th. II to Abd. V and 6-7 setae on retinaculm, and Isotomurus katule sp. nov. has a uniform body color and 5-8 setae on retinaculum. An identification key for recorded species of genus Isotomurus in Iran is provided. Color pattern as a common character used to identify Isotomurus species is not always reliable and its efficiency needs to be verified for each species.

Directional takeoff, aerial righting, and adhesion landing of semiaquatic springtails

Springtails (Collembola) have been traditionally portrayed as explosive jumpers with incipient directional takeoff and uncontrolled landing. However, for these collembolans that live near the water, such skills are crucial for evading a host of voracious aquatic and terrestrial predators. We discover that semiaquatic springtails, Isotomurus retardatus, can perform directional jumps, rapid aerial righting, and near-perfect landing on the water surface. They achieve these locomotive controls by adjusting their body attitude and impulse during takeoff, deforming their body in midair, and exploiting the hydrophilicity of their ventral tube, known as the collophore. Experiments and mathematical modeling indicate that directional-impulse control during takeoff is driven by the collophore's adhesion force, the body angle, and the stroke duration produced by their jumping organ, the furcula. In midair, springtails curve their bodies to form a U-shape pose, which leverages aerodynamic forces to right themselves in less than ~20 ms, the fastest ever measured in animals. A stable equilibrium is facilitated by the water adhered to the collophore. Aerial righting was confirmed by placing springtails in a vertical wind tunnel and through physical models. Due to these aerial responses, springtails land on their ventral side ~85% of the time while anchoring via the collophore on the water surface to avoid bouncing. We validated the springtail biophysical principles in a bioinspired jumping robot that reduces in-flight rotation and lands upright ~75% of the time. Thus, contrary to common belief, these wingless hexapods can jump, skydive, and land with outstanding control that can be fundamental for survival.

Holothuria (Lessonothuria) coronata sp. nov. (Echinodermata, Holothuroidea), a new species of sea cucumber from Socorro Island, México

?Holothuria (Lessonothuria) coronatasp. nov. occurs in depths of 5–10 m off the Mexican Pacific coast at the Revillagigedo Archipelago. It is clearly distinguished from other species of the subgenus by the presence of tables with a circular disc and big peripheral holes, sometimes with a second series of peripheral ones, a disc with a spiny or smooth rim and a spire crossed by a single cross-beam, dorsal papillae, and ventral tube feet with curved supporting rods with a spiny edge.

A remarkable new species of Hypogastrura (Collembola, Hypogastruridae) from the Romanian Carpathiansnbsp.

A new species of Hypogastrura from the Romanian Carpathians is described and illustrated. The new species is characterised by unique combination of morphological characters: presence of seven ocelli, the antennal segment IV with 4 thin, cylindrical sensilla, the presence of 5 setae on ventral tube, the short anal spines situated on high papillae and distinct chaetotaxy. The species is not easy to classify in the present system of the generic subdivision. Considering the presence of only 7+7 ocelli, the new species can be compared only with H. pyrenaica (Cassagnau, 1959), while in other morphological features it is similar to H. aterrima Yosii, 1972 and H. tethyca Ellis, 1976. The similarity between these species and systematic position of the new species are discussed.

Left-handed cardiac looping by cell chirality is mediated by position-specific convergent extensions

In the embryonic heart development of mammals and birds, a straight initial heart tube undergoes left-handed helical looping, which is a remarkable and puzzling event. We are interested in the mechanism of this chiral helical looping. Recently, observations were reported that myocardial cells in the embryonic chick heart show intrinsic chirality of rotation. The chirality of myocardial cells, via anisotropic polarization of Golgi inside the cells, leads to a left-right (LR) asymmetry of cell shape. On cell boundaries of LR asymmetric cells, phosphorylated myosin and N-cadherin are enriched. Such LR asymmetric cellular circumstances lead to a large-scale three-dimensional chiral structure, the left-handed helical loop. However, the physical mechanism of this looping is unclear. Computer simulations were performed using a cell-based three-dimensional mathematical model assuming an anterior-rightward-biased contractile force of the cell boundaries on the ventral surface of the heart (orientation of a clock hand pointing to 10 to 11 o’clock). An initially straight heart tube was successfully remodeled to the left-handed helical tube via frequent convergent extension (CE) of collective cells, which corresponds to the previously reported observations of chick heart development. Although we assumed that the biased boundary contractile force was uniform all over the ventral side, orientations of the CEs became position specific on the anterior, posterior, right, and left regions on the ventral tube. Such position-specific CEs produced the left-handed helical loop. In addition, our results suggest the loop formation process consists of two distinct phases of preparation and explicit looping. Intrinsic cell properties of chirality in this investigation were discussed relating to extrinsic factors investigated by other researches. Finally, because CE is generally exerted in the axial developmental process across different animal species, we discussed the contribution of CE to the chiral heart structure across species of chick, mouse, Xenopus, and zebrafish.

A new genus and species of Katiannidae (Collembola: Symphypleona) from Bolivia.

The new genus Borgesminthurinus gen. nov. from Bolivia shares with Sminthurinus the presence of antennal segment IV undivided, antennal segment III with one papilla; sacs of ventral tube smooth; each tenacular rami with 3 teeth and a basal appendix. They also have dens with ventral chaetotaxy reduced and lack mucronal seta; but new genus clearly differs in having thick and barbulate setae on head and body, lacking neosminthuroid setae on abdomen and the presence of seta a0 on Abd. VI acuminate. The new genus differs from Katianna which has divided antennal segment IV, vertex of head with spine-like setae and setae of the body long and smooth.

Reports of two peculiar pigmented new species of genus Homidia (Collembola:Entomobyridae) from Southern China, with description of subadults chaetotaxy.

Two new species with peculiar pigmentation of the genus Homidia from Guangdong Province, Southern China are described here, Homidia chroma sp. nov. and Homidia leniseta sp. nov. H. chroma is characterized by chrome pigmentation on lateral side of terga, two macrochaetae on medial abdominal segment (Abd.) III and six macrochaetae on postero-medial Abd. IV, up to 68 sensory chaetae present on Abd. IV, and five apical smooth chaetae on posterior face of ventral tube. H. leniseta is easily identified by unique colour pattern, smooth labial chaetae l2, G1-4 and H1-3, and short trichobothria on Abd. II-IV. Illustrations of adults of this two new species, chaetotaxy of the first instar larvae of H. chroma and subadults of H. leniseta are provided herein.

Close relationship between the genera Sinhomidia and Homidia (Collembola, Entomobryidae) revealed by adult and first instar characters, with description of a new Sinhomidia species.

A third species of the genus Sinhomidia is described from South China: S. unisetasp. nov. This new species can be distinguished from the two other species of the genus by the following characters: colour pattern, single labial chaeta M, chaetotaxy on terga and ventral tube, unguis with three inner teeth, and 15 clypeal ciliated chaetae. Also, the chaetotaxy of the first instar of Sinhomidia is described for the first time in the present paper, and confirms the close relationship between Sinhomidia and Homidia. A key to species of Sinhomidia is provided.

Structure and functions of the ventral tube of the clover springtail Sminthurus viridis (Collembola: Sminthuridae)

Springtails (Collembola) are unique in Hexapoda for bearing a ventral tube (collophore) on the first abdominal segment. Although numerous studies have been conducted on the functions of the ventral tube, its fine structure has not been thoroughly elucidated to date. In this paper, we observed the jumping behavior of the clover springtail Sminthurus viridis (Linnaeus, 1758) and dissected the ventral tube using light microscopy to elucidate the fine structure and the possible function of the ventral tube. The results show that a pair of eversible vesicles can be extended from the apical opening of the ventral tube. The eversible vesicles are furnished with numerous small papillae, and can be divided into a basal part and a distal part. The eversible vesicles have a central lumen connected to the tiny papillae and leading to the body cavity. The eversible vesicles can reach any part of the body, and may serve as following functions: (a) absorbing moisture; (b) uptaking water; (c) cleaning the body surface; and (d) fastening the body on a smooth surface.

A new Mexican species of Paraxenylla (Collembola: Hypogastruridae) from marine littoral sand of Quintana Roo, Mexico

The new species Paraxenylla mahahualana sp. nov. from Quintana Roo is described, it is similar to P. cubana , and shares the presence of ventral tube with 1 + 1 seta but differs in having tibiotarsi with 5 tenent hairs and 5 cylindrical sensilla on antennal segment IV and 3 + 3 tenacular teeth. A key for the 10 species known in the genus is also given.

Structure and function of the male ventral organ in Onychiuroides granulosus (Collembola: Onychiuridae)

On the ventral tube of males of Onychiuroides granulosus (Stach, 1934) there is a male ventral organ, which consists of two groups of four setae that are thickened, slightly flattened and bent. All setae of the male ventral organ are inserted in a richly sculptured cuticle. At the base of each seta there are a few large cells (basal cells) that have large irregular nuclei that contain a large amount of heterochromatin. In the cytoplasm of the basal cells there are numerous mitochondria, ribosomes and a rich system of endoplasmic reticulum. The plasma membrane of the basal cells forms richly folded, deep invaginations, filled with a dense material, which also occurs in particular setae and on their surface. The present study indicates that the male ventral organ is secretory and does not confirm its previously suggested sensory function.

Three new species of Coecobrya (Collembola: Entomobryidae) from caves in the Thai Peninsula

Three new species of the genus Coecobrya are described from caves in the Thai Peninsula for the first time: C. cavicta sp. nov. and C. polychaeta sp. nov. from Satun Province, and C. chumphonensis sp. nov. from Chumphon Province. These species differ in antennal length, clypeal chaetae, labial palp, sublobal chaetae of maxillary outer lobe, labial and postlabial chaetae, claw, ventral tube, manubrial plaque, and dorsal cephalic and tergal chaetotaxy. They are similar to C. annulata Zhang, Bedos & Deharveng, 2016 but differ from the latter in the combination of antennal length, claw and dorsal chaetotaxy. DNA barcoding COI sequences are provided for two species and three populations and key to the Thai species is also given. One population, which exhibits a great genetic distance (0.219–0.239) and minor but stable morphological differences from C. polychaeta sp. nov., cannot be accepted as a full species as the evidence is insufficient.

Contribution to the Willowsia species having body scales of the long basal rib type: four new species and a redescription of W. qui (Collembola: Entomobryidae)

Four new species of the genus Willowsia Shoebotham, 1917 are described from China: W. fascia Zhang & Pan sp. nov., W. pseudoplatani Zhang & Pan sp. nov., W. pseudobuskii sp. nov., and W. similis sp. nov. Willowsia qui Zhang, Chen & Deharveng, 2011 is re-described based on types and fresh material. All five species possess the pointed body scales with basal ribs longer than distal ones. These scales are absent on antennae, legs, ventral tube and furca. Colour pattern and dorsal chaetotaxy are the main diagnostic characters for these species. DNA barcodes of four species are also provided, with genetic distances compared. A key to the Willowsia species having scales of the long basal rib type is given.

New troglomorphic species of Tomocerus with well-developed postantennal organs (Collembola: Tomoceridae).

Three new troglobitic species of Tomocerus are described from the southwestern karsts of China. All of them have well developed postantennal organs. Tomocerus dong sp. nov. is similar to Tomocerus postantennalis Yu, Zhang & Deharveng and Tomocerus deharvengi sp. nov., but is different from them mainly in the number of prelabral chaetae and the dorsal body chaetotaxy. T. deharvengi sp. nov. is very similar to T. postantennalis but differs from the latter in the cephalic chaetotaxy, the number of manubrial pseudopores and the number of dental spines. T. cthulhu sp. nov. is peculiar for the multi-furcated vesicles of ventral tube, and is different from the three aforementioned species mainly in the dorsal body chaetotaxy. The position of the new species and the relationships between them are discussed.

A new cave species of the genus Protaphorura Absolon, 1901 (Collembola,Onychiuridae) from the Western Carpathians (Slovakia) with critical comments to the Palaearctic representatives of the genus.

The new species Protaphorura borinensis sp. nov. from a cave of the Western Carpathians, Central Europe, is described. It belongs to congeners with ~40 vesicles in PAO and three pseudocelli at the base of antennae and the hind margin of head. P. borinensis sp. nov. has coarse granulation of cuticle on head, and specific distribution of "s" chaetae on abdominal terga and chaetotaxy of ventral tube. Critical comments to the Palaearctic representatives of the genus Protaphorura and an identification key to 85 species are provided.