Typical Branching Pattern Research Articles

Study of Anatomical Variation of Intrahepatic Biliary Tree by Magnetic Resonance Cholangiopancreatography in Patients Attending Tertiary Hospital of Eastern Nepal

Background: There are several variations in the complex anatomy of intrahepatic bile ducts. Magnetic resonance cholangiopancreatographyis a safer imaging modality that effectively shows these variations, aiding in surgical planning and preventing iatrogenic injuries. This study aims to evaluate these anatomical variations using magnetic resonance cholangiopancreatography. Materials and Methods: This cross-sectional prospective study was performed in the Radiology Department of Nobel Medical College for one year using a convenient sampling technique. A total of 165 cases meeting the inclusion criteriawere selected and magnetic resonance cholangiopancreatography was performed to evaluate the anatomical variations. Results: The mean age of patients was 34.32±10.22 years out of which 51.5%were male and 48.5%were female. The branching pattern of right hepatic duct was typical in 66.7% of cases. The right posterior sectoral duct joining left hepatic duct was the most common variation seen in 15.2%. Right posterior sectoral duct joining the common bile duct was present in 6.7%. 6.1% of cases had unclassified variation whereas a trifurcation pattern was found in 5.5%. Left hepatic duct showed the typical branching pattern in 70.9% of cases. Segment II duct draining into the common trunk of segments III and IV was seen in 20%. Triconfluence among segments II, III, and IV was seen in 8.5% and 0.6% of cases had unclassified variation. Conclusion: This study revealed wide variation in branching patterns of intrahepatic biliary ducts. The typical branching pattern of right and left hepatic ducts were seen in majority of cases.

Anatomical variations of the aortic arch branching pattern using CT angiography: a proposal for a different morphological classification with clinical relevance.

The aortic arch (AA) branching pattern variations are usually asymptomatic, but they may lead to complications during cardiovascular procedures. In this retrospective study, we aimed to analyze the frequency of anatomical variations of the AA and to develop a different approach of morphological classification based on radiological criteria. 1026 computed tomography angiography scans of adults were evaluated and the presence of left-sided (LAA) and right-sided (RAA) AA were determined in 1023 (99.71%) and 3 (0.29%) of patients, respectively. According to the number of branches, LAA branching pattern of each patient was subclassifed in five morphological types. Based on the order and type-specific reference points, an anomalous LAA variants were classified into 20 subtypes. Type 1 (Typical branching pattern) LAA was identifed in 781 (76.12%) of the patients. Among 242 aberrant LAA variants (four types, 23.58%), the most common subtypes; Type 2A with brachiocephalico-carotid trunk (BCT), Type 4A1 with an aberrant left vertebral artery (ALVA), and Type 3A1, in which BCT coexisted with ALVA, were observed in 17.6%, 3.6%, and 0.88% of the cases, respectively. The frequency of remaining LAA variants ranged from 0.39% to 0.097%. In addition, Type 3B2 and Type 4C were first identified in our study. We observed Type I and II RAA in one female (0.097%) and two cases (male and female, 0.19%), respectively. Knowledge of AA branching variations is of great interest in neck and thoracic surgery and the new morphological types in clinically applicable form recommended in this study can be used in endovascular interventions.

Morphometry of the aortic arch and its branches. A computed tomography angiography-based study.

The current study aims to determine the prevalence of variations of the aortic arch using computed tomography angiography (CTA), as well as morphometries and gender correlations. A retrospective, transverse, observational and descriptive study of 220 CTA was performed. The branching pattern, most cranial vertebral level of the aortic arch, area of the proximal, middle and distal segments of the arch, area of each branch, and the path of atypical arteries were recorded. Results were analysed and stratified by gender. The typical aortic arch branching pattern was present in 77.7% without statistical significance between genders. The most common variant was a two-branch pattern with a common trunk and a left subclavian (13.6%), followed by a typical branching pattern with an added left vertebral artery (7.3%). T3 was the most frequent cranial level (32.3%), followed by T2-T3 (26.8%), and T3-T4 (23.2%). The mean areas of the aortic arch were 685.5 ± 183.9, 476.1 ± 124.1, and 445.0 ± 145.1 mm2 for the proximal, middle and distal segments, with statistical difference between men and women in the middle and distal segments. Three paths of atypical arteries were identified: bifurcated vertebral artery (0.5%), aberrant right subclavian artery (0.5%), and left subclavian ostium obstruction (0.5%). Mexican population has one of the highest prevalence of variations in the aortic arch branching pattern. The high probability of finding these should be taken into consideration when assessing patients. A standardised classification method would contemplate future un-reported findings, without causing confusion by the different numbers assigned by each author.

A systematic classification of the left-sided aortic arch variants based on cadaveric studies' prevalence.

Typical branching pattern of the left-sided aortic arch consists of the brachiocephalic trunk (BCT), the left common carotid artery (LCCA) and the left subclavian artery (LSA). Variant patterns have been associated with a broad spectrum of pathologies. The meticulous knowledge of potential aortic arch variants is of utmost importance to radiologists, interventional cardiologists, vascular and thoracic surgeons. The current systematic review collects all aortic arch branching patterns and their frequency as published by various cadaveric studies, calculates prevalence taking into account the gender and the different people background, as well. All extracted variant patterns are classified into types and subtypes according to the number of emerging (major and minor) branches (1, 2, 3, 4 and 5) and to the prevalence they appear. In cases of similar prevalence, total cases were taken into consideration; otherwise the variants were classified under the title "other rare variants". A systematic online search of PubMed and Google books databases was performed only in cadaveric studies. Twenty studies with typical (78% prevalence) and variable (22%) branching patterns were included. Types 3b, 2b, 4b, 1b and 5b had aprevalence of81%, of13%, of5%, 0% and of0%, respectively. Common variants were the brachiocephalico-carotid trunk (BCCT, 49% prevalence), the aberrant left vertebral artery (LVA, 41%) and the aberrant right subclavian artery (ARSA, 8%). LVA of aortic origin was detected in 32%, the bicarotid trunk (biCT) in 5% and the bi-BCT trunk in 3%. Thyroidea ima artery, a minor branch emerging from the aortic arch was found in 2%. Coexisted variants were detected in 4% (ARSA with a distinct RCCA and LCCA origin), in 3% (BCCT with a LVA of aortic origin), in 2% (ARSA with a biCT and a vertebrosubclavian trunk). No significant gender or ethnic differences exist among the 5 branching types. The proposed classification scheme aims to become a valuable and easy to use tool in the hands of all physicians involved in diagnosis and treatment of aortic arch pathology. It could be also useful in anatomical education,as well.

Collateral circulation of the femoral and genicular systems in human lower limbs is highly uncommon.

The descending branch of the lateral circumflex artery is a septocutaneous vessel that is vital for free and pedicle thigh flap transfer surgeries when repairing tissue defects. It also forms an anastomosis with the superior lateral genicular artery to create a collateral pathway for circumventing occlusions in the superficial femoral artery (SFA). Many anatomical texts and atlases imply the persistence of this anastomosis. However, previous studies indicate variability in the source of the arteries that form the anastomosis, and have reported cases where an anastomosis does not exist. We hypothesized that variations from the conventional accepted pattern can be predicted by comparisons of arterial diameters, and that unconventional anastomoses may be present to facilitate collateral circulation to the limb. Fifty-one limbs were dissected and analyzed to establish the source of the descending branch of the lateral circumflex artery, classify the types of anastomoses, and compare the diameters of the descending branch of the lateral circumflex artery, the SFA and the profunda femoris artery to the common femoral artery (CFA). Vessel diameters were normalized to the diameter of the CFA to allow comparison of limbs from both sexes and to minimize the effects of cadaver size on correlating vessel size to the presence or absence of collateral circuits. We report that 62.7% of limbs (32/51) had typical branching patterns; however, only 27.4% of limbs (14/51) had any anastomosis to connect the proximal and distal regions of the thigh. Importantly, the SFA had a wider relative diameter in limbs without anastomoses than in limbs that had normal anastomoses, perhaps precluding the formation of a collateral pathway. Overall, collateral circulation of the lower limb was highly uncommon, in contrast to information inferred from anatomical texts. This study suggests the need for more thorough procedures for determining viable anastomoses prior to thigh flap surgeries to ensure flap survival.

Anomalous Origin in the Left Circumflex Artery from the Right Coronary Artery

The typical branching pattern of the right coronary artery (RCA) consists of a marginal branch and a continuation as the posterior interventricular artery. The left coronary artery classically consists of an anterior interventricular artery and a circumflex branch, the latter of which courses around the left auricle and joins with the right coronary artery. According to past case reports, anomalies in this standard pattern are observed on angiograms with a 0.6% to 1.5% rate of occurrence (Dursunoğlu et al. 2007). Specific anomalies are found to occur at a lower rate, or are unreported due to insufficient studies and publications. Our team analyzed 23 human heart specimens (average age of 82 years) during routine cadaver dissection by undergraduate medical students and discovered an anomalous origin in the left circumflex artery (AOLCX). On the specified cadaver heart (71 year old male), an absence of the circumflex branch from the left coronary artery was noted; and upon further examination AOLCX was arising from a super‐dominant right coronary artery. After arising from the right proximal coronary artery, AOLCX wrapped around the posterior aspect of the aorta before arising anteriorly and circumflexing around the left auricle towards the posterior surface of the heart. The significance of this abnormality is that systolic compression of the AOLCX produced by the aorta and left atrium during daily activities may result in a transient reduction in coronary flow (Carboni). AOLCX from RCA has an incidence of 0.7 % (Roberts WC) and is associated with sudden death (Edwards, et al).Support or Funding InformationN/AThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Feasibility of a bone and soft tissue chimeric anterolateral thigh free flap? Anatomic study and report of two cases for oral cavity reconstruction

The anterolateral thigh flap (ALT) is a workhorse for a spectrum of reconstructive problems including head and neck defects. Its versatility as a chimeric flap employing a variety of soft tissues with a robust pedicle is useful for three-dimensional defects. The authors investigated the anatomical relationship between the vascular supply to the ALT and anterior femur. We studied 16 fresh cadaver limbs to identify the typical branching patterns to the femur off the descending branch of the lateral circumflex femoral artery. These patterns can facilitate dissection of this type of chimeric ALT. The authors have integrated a bone component of vascularised femur in this flap off the lateral circumflex femoral artery system to address oral cancer defects in two patients. A retrospective review of these cases correlating with the anatomic study was undertaken. Both patients had recurrent disease with limited donor site options. Both had extensive floor of mouth and tongue defects as well as small mandible defects of 2 cm. Both went on to heal at the donor and recipient sites at 32 months' follow-up.

Evaluation by dental cone-beam computed tomography of the incidence and sites of branches of the inferior dental canal that supply mandibular third molars

Our aim was to assess the incidence and anatomical site of branches of the inferior dental canal that supply mandibular third molars using dental cone-beam computed tomography (CT). We evaluated the incidence and diameter of branches of the inferior dental canal using 272 cone-beam CT mandibular scans from 172 patients referred for imaging before the extraction of impacted mandibular third molars. We found three typical branching patterns from the inferior dental canal in the third molar region: the retromolar canal (in the retromolar triangle), the dental canal (that courses directly beneath the socket of the third molar), and the accessory canal (that courses through the socket and leads from the inferior dental canal to a bony ridge). The incidences of retromolar, dental, and accessory canals were 75 (28%), 223 (82%), and 21 (8%), respectively, with mean diameters of 0.9 (0.4), 0.7 (0.5), and 1.1 (0.4) mm, respectively. Operative injury to the neurovascular contents within the branches of the inferior dental canal can lead to excessive bleeding and postoperative paraesthesia, so identification of its branches on preoperative cone-beam CT images may prove useful during extraction of impacted mandibular third molars or when harvesting bone blocks from the region of mandibular third molars. We also describe two cases of branches detected on panoramic and cone-beam CT images that prompted this research.

A Typical Branching Pattern of Axillary Artery in a South Indian Cadaver ? A Case Report

Knowledge of vascular variations, especially arterial variations, is very important for surgeons, radiologists and to certain extent to the other clinicians. Awareness of the possible variations will reduce the risk of complications like bleeding during surgical procedures. Occasionally these anatomical variations of arteries may result in erroneous interpretation of angiograms by radiologists. Sometimes these variations may become advantageous for the plastic surgeons in preparation of pedicle grafts. Hence we report a rare variation of high origin of superficial brachial artery from the second part of axillary artery. Superficial brachial artery continued as the main brachial artery in the arm, and terminated as radial and ulnar arteries in the cubital fossa. However the radial artery was much narrower in diameter.

Telocytes in Human Term Placenta: Morphology and Phenotype

In the last few years, a new cell type – interstitial Cajal-like cell (ICLC) – has been described in digestive and extra-digestive organs. The name has recently been changed to telocytes (TC) and their typical thin, long processes have been named telopodes (TP). To support the hypothesis that TC may also be present in human placenta and add to the information already available, we provide evidence on the ultrastructure, immunophenotype, distribution, and interactions with the surrounding stromal cells of TC in the villous core of human term placenta. We used phase-contrast microscopy, light microscopy of semithin sections, transmission electron microscopy, immunohistochemistry, and immunofluorescence of tissue sections or cell cultures, following a pre-established diagnostic algorithm. Transmission electron microscopy showed cells resembling TC, most (∼76%) having 2–3 very thin, longprocesses (tens to hundreds of micrometers), with an uneven calibre(≤0.5 µm thick) and typical branching pattern. The dilations of processes accommodate caveolae, endoplasmic reticulum cisternae, and mitochondria. These TC have close contacts with perivascular SMC in stem villi. In situ, similar cells are positive for c-kit, CD34, vimentin, caveolin-1, vascular endothelial growth factor (VEGF), and inducible nitric oxide synathase (iNOS). The c-kit-positive cells inconsistently co-express CD34, CD44, αSMA, S100, neuron-specific enolase, and nestin. Among cells with a morphologic TC profile in cell cultures, about 13% co-express c-kit, vimentin, and caveolin-1; 70% of the c-kit-positive cells co-express CD34 and 12% co-express iNOS or VEGF. In conclusion, this study confirms the presence of TC in human term placenta and provides their ultrastructural and immunophenotypic characterization.

Cogan Syndrome: Confocal Microscopy Assessment of Corneal Damage

To perform in vivo assessment of corneal alterations in patients with Cogan syndrome (CS) and to correlate these findings with prior histopathologic descriptions. Four consecutive patients (8 eyes) presenting with typical CS underwent confocal microscopy examination. At the moment of evaluation, ocular inflammation was quiescent in all the patients. The images were studied singularly, and then compared to those obtained from 5 healthy controls. Statistical analysis was performed with Student t test. All the cases showed multiple brightly reflective deposits in the stroma with moderate reflectivity of the surrounding stromal tissue. The outer corneal layers and the endothelium were spared. In 3/4 of the patients, the nerve fibers of the subepithelial plexus were thin and poorly reflective, with interruptions and lack of the typical branching pattern. No cells different from keratocytes could be detected in either case or control eyes. Corneal vascularization was present in one case. In CS-affected eyes, corneal thickness was 552+/-62 microm on average, and endothelial cell count was 2466+/-288 cells/mm(2). Statistical significance was not reached compared to the control group. Confocal microscopy was able to provide detailed images of corneal alterations in CS. This confirmed the interstitial nature of the keratitis and showed an excellent accordance with prior histopathologic findings. The absence of inflammatory cell infiltration may be explained by the prolonged control of ocular inflammation in our patients, which may also have limited stimuli for corneal neovascularization.

Noradrenergic modulation of calcium currents and synaptic transmission in the olfactory bulb of Xenopus laevis tadpoles.

Norepinephrine (NE) has various modulatory roles in both the peripheral and the central nervous systems. Here we investigate the function of the locus coeruleus efferent fibres in the olfactory bulb of Xenopus laevis tadpoles. In order to distinguish unambiguously between mitral cells and granule cells of the main olfactory bulb and the accessory olfactory bulb, we used a slice preparation. The two neuron types were distinguished on the basis of their location in the slice, their typical branching pattern and by electrophysiological criteria. At NE concentrations lower than 5 microM there was only one effect of NE upon voltage-gated conductances; NE blocked a high-voltage-activated Ca(2+)-current in mitral cells of both the main and the accessory olfactory bulbs. No such effect was observed in granule cells. The effect of NE upon mitral cell Ca(2+)-currents was mimicked by the alpha(2)-receptor agonists clonidine and alpha-methyl-NE. As a second effect, NE or clonidine blocked spontaneous synaptic activity in granule cells of both the main and the accessory olfactory bulbs. NE or clonidine also blocked the spontaneous synaptic activity in mitral cells of either olfactory bulb. The amplitude of glutamate-induced currents in granule cells was modulated neither by clonidine nor by alpha-methyl-NE. Taken together, the main effect of the noradrenergic, presynaptic, alpha(2)-receptor-mediated block of Ca(2)+-currents in mitral cells appeared to be a wide-spread disinhibition of mitral cells in the accessory olfactory bulb as well as in the main olfactory bulb.

Unusual aortic arch variation: Distal origin of common carotid arteries

As part of a larger study, the aortic arch and its branches were removed en bloc at autopsy from men of Japanese ancestry born in Hawaii. Of the 193 arterial trees examined, 182 (94.3%) had a typical branching pattern (e.g., brachiocephalic trunk, left common carotid, and left subclavian arteries, in that order). Two specimens had only two branches arising from the aortic arch, a common trunk uniting the brachiocephalic and left common carotid arteries and a left subclavian artery. Nine individuals (4.6%) had four branches off the aortic arch; in eight of these cases (4.1%), the left vertebral artery originated directly off the aortic arch just proximal to, or as a common trunk with, the left subclavian artery. A unique aortic arch branching pattern was found in one of these men. The four arteries arising from the arch of the aorta were, in sequence: right subclavian, left subclavian, right common carotid, and left common carotid. The literature on aortic arch variations is reviewed and the possible embryonic development of these branching patterns and their clinical significance is discussed briefly.

Unusual aortic arch variation: Distal origin of common carotid arteries

As part of a larger study, the aortic arch and its branches were removed en bloc at autopsy from men of Japanese ancestry born in Hawaii. Of the 193 arterial trees examined, 182 (94.3%) had a typical branching pattern (e.g., brachiocephalic trunk, left common carotid, and left subclavian arteries, in that order). Two specimens had only two branches arising from the aortic arch, a common trunk uniting the brachiocephalic and left common carotid arteries and a left subclavian artery. Nine individuals (4.6%) had four branches off the aortic arch; in eight of these cases (4.1%), the left vertebral artery originated directly off the aortic arch just proximal to, or as a common trunk with, the left subclavian artery. A unique aortic arch branching pattern was found in one of these men. The four arteries arising from the arch of the aorta were, in sequence: right subclavian, left subclavian, right common carotid, and left common carotid. The literature on aortic arch variations is reviewed and the possible embryonic development of these branching patterns and their clinical significance is discussed briefly.

Gross anatomic evidence of partitioning in the human fibularis longus and brevis muscles.

Evidence from a variety of studies suggests that many mammalian muscles are partitioned with respect to their architecture and innervation. Each of these specific muscle subvolumes is innervated by an individual muscle nerve branch, contains motor unit territories with a unique array of physiological attributes and has been known as a neuromuscular compartment or segment. This gross anatomic study investigated for evidence of neuromuscular segmentation in human fibularis (peroneus) longus and brevis muscles. Forty-three legs (24 left, 19 right) from embalmed adult cadavers were dissected. Any architectural segment within these muscles were identified. The specific innervation patterns of these muscles were also described. The fibularis longus muscle was consistently found to have connective tissue partitions that separated it into four parts: anterior superficial, anterior deep, posterior superficial, and posterior deep. The innervation pattern of this muscle was consistent with the segments defined by the connective tissue partitions. There were consistently four primary motor branches, each supplying a specific portion of the fibularis longus muscle. While a typical branching pattern was recognized, there was some variability as to the order of these branches as they originated. The fibularis brevis muscle was consistently found to have a central connective tissue partition that separated it into two portions: anterior and posterior. In 91% of the fibularis brevis muscles, there were two primary motor branches, one for each of the two segments of the muscle. In the other 9%, only one primary motor branch supplying the muscle could be identified.

Alpha ganglion cells in mammalian retinae: Common properties, species differences, and some comments on other ganglion cells

A specific morphological class of ganglion cell, the alpha cell, was first defined in cat retina. Alpha cells have since been found in a wide range of mammalian retinae, including several orders of placental and marsupial mammals. Characteristically, they have the largest somata and a large dendritic field with a typical branching pattern. They occur as inner and outer stratifying subpopulations, presumably corresponding to ON-center and OFF-center receptive fields. In all species, alpha cells account for less than 10% of the ganglion cells, their somata are regularly spaced, and their dendritic fields evenly and economically cover the retina in a mosaic-like fashion. The morphology of alpha cells and many features, both of single cells and of the population, are conserved across species with different habitats and life-styles. This suggests that alpha cells are a consistent obligatory ganglion cell type in every mammalian retina and probably subserve some fundamental task(s) in visual performance. Some general rules about the construction principles of ganglion cell classes are inferred from the alpha cells, stressing the importance of population parameters for the definition of a class. The principle, that a functionally and morphologically homogeneous population should have a regular arrangement and a complete and even coverage of the retina to perform its part in image processing at each retinal location, is especially evident across species and across ganglion cell types.

Hartig net structure and formation in fully ensheathed ectomycorrhizas

The structure and formation of the Hartig net was examined in four different types of spruce ectomycorrhizas from the field. The investigations confirmed that in the case of mycorrhizas with a fully developed sheath enclosing the root apex, the Hartig net is formed by a highly branched fingerlike or puzzlelike hyphal system.It is shown that the hyphae penetrate and grow mainly in a transversal direction to the axis of the root, resulting in typical indentation patterns on some tangential walls and a fountainlike separation of hyphae when growing from the radial to the tangential intercellular spaces. Septae formation within the branched hyphal system of the Hartig net is rare. Structures which, in sections, appear to be incomplete septae are explained as the result of the branching pattern.The alignement and the typical branching pattern of the Hartig net is also found around the outermost cortical cells. A description of the changing structure in the different layers of a pseudoparenchymatous hyphal mantle is given. Finally, details of the three‐dimensional structure of the mantle and the Hartig net are represented in a block diagram.

Localization of NPY-immunoreactivity in the cat's visual cortex.

Using a polyclonal antiserum against neuropeptide Y (NPY; J.M. Allen et al. 1983a) immunohistochemistry was carried out using the PAP method. Neurones displaying NPY-like immunoreactivity are seen mainly in cortical layers V/VI, adjacent white matter and corona radiata. Only few neurones occur in superficial layers II/III. Neurones are multipolar to bitufted with spineless dendrites; somata are either round (layers V, II/III) or spindle-like (layer VI, white matter) with diameters between 16 and 20 microns. Axons were identified by their initial smoother profiles, which are smaller in diameter than principal dendrites, by their typical branching pattern and the occurrence of terminal portions. It was found, that the degree of axonal ramification in proximal parts of axons is rather poor. Most NPY-neurones seem to project intracortically or even locally, except neurones in layers VI and the white matter. The latter neurones have ascending axonal branches terminating in layer VI and V, thus contributing to the dense NPY-plexus in these layers, whereas some layer VI neurones have axonal branches descending into the white matter. The axonal plexus in upper cortical layers is most probably fed by the ascending axons of layer V neurones, passing layer IVc in a strictly vertical direction. Fine smooth fibers of unknown origin which ascend from the white matter in a vertical direction through the grey matter also contribute to the plexus in layer II/III. In semithin sectioned material three terminal types were identified. Firstly, en passant boutons on immunonegative pyramidal neurones, secondly, perisomatically arranged, basket-like terminals, bending around unstained non-pyramidal neurones, and thirdly, about 60 microns long vertically oriented rows of boutons exclusively on apical dendrites of layer II/III pyramidal neurones. Due to the unconspicious axonal pattern and the frequently observed basket-like terminal form, we conclude that most NPY-ir neurones can be regarded as a class of unspecific local field basket cells; the origin of the vertically arranged bouton rows has been yet to determined.

A study onGracilaria dendroidessp. nov. (Gigartinales, Rhodophyta) from the Bay of Naples

Gracilaria dendroides sp. nov. is described from the Bay of Naples, Italy, where it thrives on the rocks in the upper littoral. The species has a typical branching pattern resulting in the dendroid habit of the plant. G. dendroides is also characterized by lanceolate branchlets which become longer and taper in the distal part of the branches. Tetrasporangia, spermatangial conceptacles and cystocarps are localized in the lanceolate branchlets. The cortex in which tetrasporangia are deeply immersed is modified, the cells being less vacuolized and with a thick cell wall. The spermatangial conceptacles are as in G. verrucosa. The gonimoblastic tissue is lobate with connective filaments to the pericarp. The morphological and structural features are considered stable thus supporting the description of a new species.