Multi-loci phylogeny and morphological evidence support the recognition of Januaria (Spermacoceae, Rubiaceae), a new monospecific genus endemic to the North of Minas Gerais (Brazil)

Abstract Januaria is described as a new monospecific genus of Rubiaceae, based on material from Januária, northern Minas Gerais, Brazil. The new taxon is endemic to Brazil, occurring in a vegetation type that is known locally as “carrasco”, in the southern limit of the Caatinga biome. Morphological (including palynological and SEM analyses) and molecular phylogenetic analyses based on nuclear (ETS, ITS) and plastid (atpB-rbcL, peth, rps16, trnL-trnF) sequence data were performed in the Spermacoce clade (tribe Spermacoceae). The molecular position and morphological features (a unique fruit dehiscence type, and pollen exine with simple reticulum) support Januaria as a new genus, with Mitracarpus as sister group, from which it differs principally in calyx morphology, corolla shape, and fruit dehiscence. Additionally, a further comparison with other morphologically similar genera is presented. We provide a formal description of Januaria, together with a distribution map and comments on its conservation. In addition, a discussion about the Brazilian endemics of the Spermacoce clade is given, also with a key to all the genera of this group present in the country.


INTRODUCTION
The Rubiaceae is a family that comprises mainly shrubs or trees, however a few lineages within the family include herbaceous species (Robbrecht & Manen 2006).The tribe Spermacoceae (sensu Andersson & Rova 1999) is the largest herbaceous lineage of the family, with over 1000 species in c. 80 genera (Groeninckx et al. 2009, Gibbons 2020, Nuñez-Florentin et al. 2022, Carmo et al. 2022).Tribe Spermacoceae s.s.(sensu Robbrecht 1988, coinciding with the classical definition) -currently known as Spermacoce clade -is historically one of the most challenging lineages in the fourth largest family of flowering plants.From a morphological point of view, the Spermacoce clade is easily recognizable from the following combination of characters: herbaceous plants, presence of raphids, fimbriate stipules, uniovulate ovary locules, and pluri-aperturate pollen grains.
In America, the Spermacoce clade is currently represented by 23 genera, including the recently described genus Paganuccia R.M. Salas (Nuñez-Florentin et al. 2022).In 2015, Salas et al. published the first phylogenetic study focussing on the Spermacoce clade using nuclear markers (ITS and ETS), thereby describing the new genus, Carajasia R.M. Salas, E.L. Cabral & Dessein, based on morphological and molecular evidence.Despite various taxonomic and phylogenetic studies carried out in the past to further revise and elucidate generic boundaries and phylogenetic relationships within the Spermacoce clade (Miguel & Cabral 2013, Salas et al. 2015, Florentín et al. 2017, Miguel et al. 2018), there are still different opinions among specialists on the delimitation of some genera (e.g.Spermacoce-Borreria complex).
The north of Minas Gerais (Brazil) is an area characterized by predominantly xerophytic and deciduous vegetation, which constitutes a mosaic of physiognomies, or vegetational complexes.It is also considered as the southern limit of the Caatinga biome, an area of transition between the Caatinga and the Cerrado (Velloso et al. 2002, Queiroz 2006, Queiroz et al. 2017, Fernandez et al. 2020).Lombardi et al. (2005) conducted a floristic survey in this area, specifically in the municipality of Januária.Among the arboreous/shrub Rubiaceae taxa founded, the authors identified one specimen as "Borreria sp."During a recent herbarium study, this specimen was analysed in greater depth and although the primary traits indicated that it undoubtedly belongs to the Spermacoce clade, a more detailed analysis revealed that it could not be considered as a member of the genus Borreria G. Mey (following the concept of Miguel & Cabral 2013) or another morphologically similar taxon (e.g.Spermacoce L. sensu Nuñez-Florentin et al. 2020).
Therefore, in order to elucidate the taxonomic position of this new taxon, a molecular phylogenetic analysis of the Spermacoce clade was carried out using molecular markers from the nuclear ribosomal (ITS and ETS) and chloroplast genomes (atpB-rbcL, petD, rps16, and trnL-trnF).By applying a complementary molecular and morphological analysis (e.g., fruit dehiscence, pollen, and seed observations), the evolutionary history of the new taxon and its relatives could be inferred.In addition, a geographic overview of Brazilian Spermacoceae, focused on endemic genera of Spermacoce clade is given.

Taxonomic treatment and conservation assessment
Conventional taxonomic techniques were followed for the description and analysis of the new monotypic genus and its species.Additional data was retrieved from herbarium specimens from BHCB and W [herbarium codes according to Thiers (2021, continuously updated)].Information concerning the habitat, flowering period, and qualitative characteristics, such as the colour of the flowers, were obtained from the herbarium labels.
An assessment of the conservation status was carried out following the IUCN Standards and Petitions Committee (2019) recommendations.

Morphological analyses
For the morphological observations, floral and vegetative parts were rehydrated in warm soapy water and analysed under a stereomicroscope (SM) Leica MZ6 and measured using an electronic digital caliper (Schwyz).The morphological terminology follows Stearn (1986).For scanning electron microscopy (SEM) analyses, flowers were obtained from herbarium material and rehydrated for 12 hours in water at 60°C with a drop of detergent.After the preparation step, the material was dried to critical point with CO 2 and mounted on aluminium stubs.Fruits and seeds were mounted on aluminium stubs without any treatment.All material was sputter coated with 20 nm of gold-palladium.Observations were performed at 20 kV with a SEM Jeol LV 5800 at the Electron Microscopy unit of the Universidad Nacional del Nordeste (UNNE).

Palynological analyses
Pollen grains were acetolysed according to the technique described by Erdtman (1966) and mounted in glycerine jelly for analysis by light microscopy (LM).The shape of the pollen grains, the ratio of the polar axis (P) and the equatorial diameter (E) were studied by photographing at least 20 grains with a LM Leica DM LB2 microscope equipped with a digital camera and then measured afterwards using the program ImageJ v.1.51k(Rasband 2020).The exine structure was analysed using SEM.The morphological terminology for pollen follows Punt et al. (2007).

Taxon and gene sampling
The sampling included 77 ingroup accessions from the Spermacoce clade (Appendix I; Fig. 1).The present sampling represents approximately 30% of the species and 80% of the genera of the Spermacoce clade.Two nuclear ribosomal (ITS, ETS) and four plastid (atpB-rbcL, petD, rps16, trnL-trnF) DNA regions were selected since they have proven to be phylogenetically informative within the Rubiaceae (Kårehed et al. 2008).The new sequences were added to existing alignments used by Nuñez-Florentin et al. (2021, 2022).Bouvardia ternifolia Cav. was chosen as an outgroup taxon based on its placement in previous phylogenetic analyses (Kårehed et al. 2008, Salas et al. 2015).The full details of the vouchers used in the phylogenetic inference analysis are provided in Appendix I.

DNA extraction, amplification, purification, and sequencing
In order to assess the phylogenetic position of the new taxon within the Spermacoce clade, its genomic DNA was extracted from herbarium material, using a modified CTAB protocol (Doyle & Doyle 1987) according to the protocol outlined by Janssens et al. (2006).Amplification reactions were carried out on a GeneAmp PCR system 9700 (Applied Biosystems) for six markers, two nuclear (ITS, ETS), and four plastid (atpB-rbcL, petD, rps16, trnL-trnF).Primers and thermocycler programs used for the amplification of nuclear and plastid markers were those described in Nuñez-Florentin et al. (2022).Purified amplification products were sent to Macrogen, Inc. (Seoul, South Korea) for sequencing.DNA extraction, PCR and amplification were carried out at the molecular lab of Meise Botanic Garden.

Alignment and phylogenetic analyses
The sequences were edited and assembled de novo using Geneious v11.1.4 (Biomatters,Auckland,New Zealand).Automatic multiple alignments were carried out with AliView (Larsson 2014), using the Muscle algorithm, also with subsequent manual editing to improve homology for more variable regions.The combined matrix (nuclear + plastid markers) is available in Supplementary Material -Alignment. combined  "the nuclear matrix", "the plastid matrix", and the "nuclear + plastid combined matrix" (in the absence of supported conflict between the resulting gene trees).For the combined analyses, a mixed model approach was used in which the data set was partitioned, and the models of evolution were applied to the different partitions.Two independent Metropolis coupled Markov chain Monte Carlo (MCMC) runs, each consisting of one cold and three heated chains, were started simultaneously from a random tree and run for 20 million generations, with the trees being sampled every 10,000 generations.At the end of the run, chain convergence and estimated sample size (ESS) parameters were assessed with Tracer v.1.6.0 (Rambaut et al. 2014).Burnin was set at 25% and the remaining posterior topologies summarized as a 50% majority-rule consensus tree, with branch support expressed as posterior probabilities (PP).PP values from 0.5 to 0.95 were considered as weak to moderate support, whereas posterior probabilities > 0.95 were considered as strong to very strong support (Suzuki et al. 2002, Alfaro et al. 2003).ML analyses were performed using RAxML-MPI v.8.2 (Stamatakis et al. 2008), as implemented on the CIPRES Science Gateway web server ( RAxML-HPC2 on XSEDE 8.1.11) (Miller et al. 2010), with the following settings: rapid bootstrap analysis with 1000 replicates and searching for the best-scoring ML tree starting with a random seed and utilizing the GTRGAMMA model.Rapid bootstrapping was performed on the ML tree using RAxML at 1000 replicates to determine branch support.Only the ML bootstrap (BS) values (≥ 0.5) are provided.Internodes with BS ≥75% were considered statistically significant.
Congruency between the different datasets was inferred using different methods.Due to the known sensitivity issues of the ILD test (Barker & Lutzoni 2002), possible conflict between the marker datasets was also assessed by visually inspecting the topologies, thereby searching for putatively conflicting relationships and the way those were supported within each topology (hard vs. soft incongruences; Johnson & Soltis 1998, Wiens 1998).

Geographic distribution
The geographic record obtained was plotted in QGis 3.4.2-Madeira (QGIS Development Team 2018).The distribution of the species was superimposed with a layer of the Ecoregions derived from Olson's classification (2001).To study the distribution of the species in relation to protected areas (PAs), we used spatial data from the world database on protected areas (WDPA https://protectedplanet.net/; visited in October 2021) and from Dinerstein et al. (2017).

Properties of the sequence data
Dataset characteristics and models of nucleotide substitution selected by AIC are presented in Table I.The nuclear ITS and ETS DNA regions were more phylogenetically informative than the four plastid markers.Of the 632 aligned ITS characters, 210 potentially informative sites (33.2%) were obtained, and ETS yielded 186 informative sites out of 364 characters (51.1%), for a total of 396 potentially informative nuclear characters, out of a total of 996 (39.8%).The aligned lengths of the four plastid markers ranged from 458 bp (trnL-trnF) to 1155 bp (petD), and all together they yielded 3068 characters, of which 212 (6.9%) were informative.

Separate analyses and assessment of incongruence
The individual nuclear and plastid gene datasets were first analysed separately (results available as Figures S1, S2).Most of them resulted in polytomies or only produced poorly resolved clades, except for the ITS and ETS, which provided the highest proportion of well-resolved clades.No significant incongruence or decreased resolution was observed after analysing a combined nuclear (ITS + ETS) dataset versus a combined plastid (atpB-rbcL + petD + rps16 + trnL-trnF) dataset.

Combined plastid and nuclear analyses
The concatenated ML trees (Figure S2) were very similar to the Bayesian topologies, therefore, only the 50% majority rule Bayesian consensus tree from the combined analysis (nuclear + plastid data) is shown and used for further discussion (Fig. 1).

Taxonomic treatment
In the following paragraphs we present the formal description of the new genus and species based on morphological and phylogenetic evidence.

Diagnosis
The genus Januaria (consisting of a single species J. lombardii) differs from all the other genera of the Spermacoce clade due to the particular fruit dehiscence (dehiscence longitudinal-transverse, with a longitudinal-septifragal dehiscence that starts in one of the carpels up to the middle of the fruit, and from there, it follows an transverseloculicidal line, resulting in one indehiscent carpel remaining on the pedicel and another dehiscent carpel which falls off and releases the seed) and 8-zonoaperturate pollen grains with simple reticulate exine pattern.

Distribution and Habitat
Januaria is endemic from Minas Gerais (municipality of Janúaria), Brazil.Figure 4a represents the geographic distribution of this new taxon, which coincides with the ecoregion "Brazilian Dry Atlantic Forest" from Olson's classification (2001).According to the information on the label of the collected specimen, this species occurs in a vegetation type that is known locally as "carrasco" (see further details in Discussion section).

Phenology
The sole specimen of this taxon was collected in May and contained flowers, floral buds and mature fruits, indicating that the fertile period of this species could cover the months from December to May-June approximately, coinciding with the rainy season.

Etymology
The generic name refers to the locality where the holotype was collected, Januária, Minas Gerais, Brazil.The specific epithet honours Julio Antonio Lombardi, who collected the holotype of Januaria lombardii, and has made significant contributions to the study of the Brazilian Flora,

Preliminary conservation status
Januaria is known from a single collection from the Cavernas do Peruaçu National Park, a conservation unity of 564.48 km², located in the municipalities of Itacarambi, Januária, and São João das Missões.Even though the vegetation cover within the limits of the park is relatively well preserved, its adjacent areas, as well as most of the north of Minas Gerais are in constant transformation due to increased anthropogenic land use (Fig. 4b).Although extensive field work was carried out in April-May 2012, no additional populations of the species were found.Accordingly, based on the available information, and following the criteria and recommendations of the IUCN Red List Status (2019) and Callmander et al. ( 2005), we consider this new taxon as Vulnerable (VU), under criterion D2, for the time being.

Notes
Due to its morphological characteristics, especially compressed, axillary, pauciflorous, inflorescences with homostylous flowers the new taxon resembles some species of Borreria, Hexasepalum, and Spermacoce.However, it differs from each of them due to the unique The ecoregion protection categories are defined as follows: Nature Could Recover, the sum of the amount of natural habitat remaining and the amount of the total ecoregion that is protected is less than 50% but more than 20%; Nature Imperiled, the sum of the amount of natural habitat remaining and the amount of the total ecoregion that is protected is less than or equal to 20%.
dehiscence of its fruits, by the 8-zonoaperturate pollen grains with simple reticulum (vs.primarily perforate to perforate-microreticulate, and eutectate in Borreria, Hexasepalum, and Spermacoce) and the presence of a shortly branched, bifid stigma (vs.capitate-bilobate to bilobate in Borreria, Hexasepalum, and Spermacoce).For a further comparison between these taxa see Table II.In the vegetative state, they are very similar, and maybe this is the reason for the scarce collections and/or misidentification.

DISCUSSION
The phylogenetic position of Januaria in the Spermacoce clade, and its distinctive morphology The topologies recovered in the current study agree with previous studies of the Spermacoce clade that were obtained from nuclear data only (Salas et al. 2015, Florentín et al. 2017, Miguel et al. 2018) or from a combined nuclear and plastid data matrix ( Nuñez-Florentin et al. 2021, 2022).
Using molecular sequence data, we demonstrated that new described taxon, Januaria lombardii, belongs to the Spermacoce clade, one of the most taxonomically complex groups within the tribe Spermacoceae (for discussion see Groeninckx et al. 2009, Salas et al. 2015).Specifically, the new taxon is recovered within clade "B", in closed relationship with the genus Mitracarpus (Fig. 1).
Mitracarpus is a morphologically and phylogenetically well circumscribed Neotropical genus (Souza et al. 2010), strongly supported, but largely unresolved in relationship with the other genera of the Spermacoce clade (Salas et al. 2015, Nuñez-Florentin et al. 2021, 2022).In the present analyses, Januaria, results a monospecific genus sister to Mitracarpus, from which it differs by its calyx morphology (4 lobes of the same length vs. 2 smaller lobes and 2 larger lobes), corolla shape (infundibuliform vs. hypocrateriform), seed morphology (ellipsoid seed with a longitudinal ventral groove vs. ovoid or ellipsoid seed with a quadrangular or rectangular, "X-shaped" or "inverted Y-shaped" ventral groove), and fruit dehiscence (longitudinal-transverse dehiscence with one dehiscent carpel and one indehiscent carpel vs. circumscissile dehiscence, with both dehiscent carpels).For a further comparison with Mitracarpus and other morphologically similar genera see Table II.
One of the most striking features of Januaria is the fruit dehiscence, which is unique within the Spermacoce clade.The taxonomic value of the fruit morphology in the Spermacoce clade has already been shown in the description of the tribe Spermacoceae by Berchtold & Presl (1820).Subsequently, classic taxonomists, such as Candolle (1830) or Schumann (1888, 1891), considered the type of dehiscence as the only criterion to support or conserve genera.There are some genera in which the fruit morphology is so unique that their circumscription is based on only that particular character (e.g.Mitracarpus, Ernodea, Crusea).The main role attributed to the type of dehiscence has resulted in several taxa that have been considered artificial groups, not supported by morphological characters other than such features (e.g.Diodia L., Borreria, Spermacoce, Staelia, etc. Cabaña Fader 2013, Miguel 2016, Salas 2011).Therefore, in the case of the genus Januaria, the longitudinal-transverse dehiscence in combination with the specific morphological pollen characters and the phylogenetic position support its recognition as a new genus.(Pire 1996, Sobrado 2015)].According to the pollen size, shape, number of apertures, and colpi length, the pollen grains of Mitracarpus robustus, Spermacoce congestanthera, and Staelia catolensis are those that most closely resemble J. lombardii, yet they differ from the latter in a few slightly different features.Mitracarpus robustus has 9-10 aperturate pollen grains, whereas Januaria is (7-) 8 aperturate.Furthermore, while Staelia catolensis has a micro-reticulate to reticulate ornamentation pattern with a lumina size of 0.1-1.2µm, Januaria has a reticulate exine with larger lumina (1.1-2.1 µm).In addition, Spermacoce congestanthera has colpi that are middle sized to short in length, whereas the ectocolpi of Januaria pollen are long.As a result, J. lombardii pollen has a morphological affinity with pollen type 20, as proposed by Dessein et al. (2005) and then expanded by Salas & Cabral (2014).Table III presents a detailed comparison of the palynological characteristics between J. lombardii and other taxa with a reticulate exine.

The endemism and habitat of Januaria
Following the regionalization by Olson et al. (2001), the only georeferenced location known for J. lombardii shows that inhabits the Brazilian Atlantic Dry Forest, in an ecotonal region between Caatinga and Cerrado ecoregions (Fig. 4a).The Carrasco (a local name for sedimentary Caatinga) is sometimes referred to as being composed of a mix of seasonally dry tropical forests and woodlands (SDTFW sensu Queiroz et al. 2017) and savanna elements (Araújo et al. 1998, Fernandez et al. 2020).According to the information on the label, J. lombardii was collected in this vegetation type called "Carrasco", characterized by a mainly deciduous shrub-tree vegetation composed of plants that are mostly no higher than 5m tall, with only a few species reaching 10m.Herbs and climbers are common in the forest margins or along roads but are rare in the interior of the vegetation (Lombardi et al. 2005).
The floristic study of Lombardi et al. ( 2005) highlights the floristic and physiognomic diversity of Januária, northern of Minas Gerais, and emphasizes the importance and urgency of inventories for the region as it is of high priority for conservation due to the enormous anthropogenic pressure caused by the continuously advancing agricultural frontier and the new mining concessions.In this sense, Fernandez et al. ( 2020) noted the importance of the border areas of the Caatinga and stated that "the adjacency and connectivity of different biomes within such a small area provide geographic opportunities for ecologically labile species to expand their ranges and be recorded in different biomes even within a small geographic area".
Even though the new genus Januaria occurs within the limits of a protected area (National Park Carvernas do Peraçu, Fig. 4b), the national park and adjacent areas are currently considered as "Nature imperiled" areas by Dinerstein et al. (2017).Dinerstein and coauthors organized the 846 ecoregions recognized worldwide into four distinct categories, defined by the extent of the remaining natural habitat and protected land.The category "Nature imperiled" refers to regions in which the protected area is less or equal to 20% where the remaining habitat exists as a mosaic of isolated fragments insufficient in size and orientation to adequately conserve biodiversity.In addition, more recently, Peixoto Teixeira et al. (2021) using GIS, quantified the total area of Caatinga encompassed by fully protected and sustainable use reserves.The authors found that less than 8% of the Caatinga is legally protected under Brazil's national nature reserve legislation (SNUC law), and only 1.3% is in reserves with full legal protection.Therefore, Dinerstein et al. (2017) andPeixoto Teixeira et al. (2021) agreed with previous authors (e.g.Miles et al. 2006, Queiroz et al. 2006), that the tropical dry forest is one of the most endangered biomes in the world, and despite a recent expansion of the protected area network, only small portions of the Brazilian semiarid region are effectively safeguarded.

Endemism of Spermacoce clade in Brazil
As stated by Lombardi et al. (2005) the wide variety of vegetation types in a relatively small sample area, such as in the north of Minas Gerais, is probably conditioned by edaphic factors, including the capacity of the soil to retain water.The whole Brazilian territory shows similar conditions, thereby exhibiting a large expanse of several biomes, with different types of vegetation and remarkable plant diversity.
Studies on the ancestral area reconstruction and diversification are still lacking in the Spermacoce clade, but it has been hypothesized that the Neotropics is the centre of origin for the Spermacoce clade (Dessein 2003, Janssens et al. 2016).According to our knowledge, Brazil comprises 16 of the 24 currently recognized genera of the Spermacoce clade.Of these, seven genera are endemic to the country: Carajasia, Denscantia E.L. Cabral & Bacigalupo, Paganuccia, Planaltina R.M. Salas & E.L. Cabral, Psyllocarpus, Schwendenera is endemic to the Atlantic Forest, ocurring in the interior or along the margin of the humid forest biome in the south of Brazil (São Paulo and Paraná states) (Salas et al. 2020).Paganuccia is a recently described monospecific genus ( Nuñez-Florentin et al. 2022), endemic to the dune areas of the mid São Francisco River valley (Bahia), occurring in the Caatinga.Carajasia is also a monotypic genus with a restrictive distribution, being endemic to Pará in the north of Brazil, where it only grows in ferric soil (or Canga) on the top of the Carajás mountain range (Salas et al. 2015).
Paganuccia and Carajasia are similar to Januaria in that they are all recently described genera based on new or hitherto unstudied, or unidentified, herbarium material from areas with limited access.Their limited access could explain why these areas are poorly explored botanically resulting in large collecting deficits.As Fernandez et al. (2020) argues: "further botanical exploration with increased collecting efforts and taxonomic revisions of plant diversity, especially understudied families, may potentially reveal larger numbers of flowering plants in the dry forests, especially in the Caatinga; and that the discovery of new taxa is inevitable in light of the large number of unidentified specimens in Brazilian herbaria".In this sense, Bebber et al. (2010) mentioned that only 16% of the flowering plants are described within five years of being collected for the first time.The description of the remaining 84% involves much older specimens, with nearly 25% of new species descriptions involving specimens that are over 50 years old.Extrapolation of these results suggests that, of the estimated 70,000 species still to be described, more than half have already been collected and are stored in herbaria.Januaria lombardii is indeed a good example of this interesting scenario.This taxon was collected twice, one collection by Julio Lombardi in 1997, and the oldest specimen probably collected in the middle of the nineteenth century (Gardner's paratype), i.e., the genus remained indeterminate in a herbarium for more than 100 years.Supporting Bebber et al. (2010), a study also performed in the Spermacoce clade, resulted in the recently described new species of Staelia overlooked for more than a century (Staelia schumannii R.M. Salas & E.L. Cabral, Carmo et al. 2021).
In view of the above, we provide an updated key to all the genera of the Spermacoce clade in Brazil (adapted from Nuñez-Florentin et al. 2022).3 3. Fruits indehiscent or fruits tardily separated at the apex into two indehiscent carpels.Seeds wingless or shortly winged [Bahia].Paganuccia 3. Fruits septicidally dehiscent, dividing into two valves.Seeds winged, wing derived from a strophiole that exceeds the base and apex of the seed or from an extension of the exotesta 4 4. Flowers pedicellate, pedicel 1.7-5.5 mm long.Fruit with an apical portion of the carpels exceeding the hypanthium and forming a "beak" or "rostrum".14 13.Calyx 4-lobed, with 2 larger and 2 smaller lobes, rarely exceptions.Corolla mostly hypocrateriform.Fruit with circumscissile dehiscence; the fruit separates into two parts after dehiscence, the superior part in the shape of a "mitre" formed by the upper portion of the carpels and persistent calyx lobes, and the inferior part formed of the basal portion of the carpels and basal part of the septum [widespread].

Key to the genera of
Mitracarpus 13.Calyx 2-lobed (rarely 3-4), with lobes equal or subequal.Corolla infundibuliform.Fruit with longitudinal-oblique dehiscence, fruit separated into three parts after dehiscence, two apical caducous valves, and a basal portion formed of the basal portion of the carpels, and an intercarpellar septum that remains intact and persists on the plant [widespread].

CONCLUSION
This study further unravels the complex phylogenetic relationships within the Spermacoce clade as part of an ongoing global revision of the group.It also further improves the taxonomic classification of the Spermacoce clade.In this opportunity, we present the description of an endemic, and probably endangered, new genus, with a combination of phylogenetic and morphological evidence.Nevertheless, many issues remain unsolved in the classification of the Spermacoce clade (tribe Spermacoceae) and further sampling will be required (especially of those poorly known taxa) in order to provide further improvements.
To prevent an irreversible loss of biodiversity, more attention and funding must be devoted to the protection of the Brazilian dry forest and the many endemic species that are characteristic of these notable ecosystems.Furthermore, we believe that the description of this new taxon, despite being a unicate, is extremely important considering that the area it inhabits is clearly threatened.This is a contribution to the recent checklists of floristic information about the Caatinga, considered as a first large step in the increase in scientific knowledge, fundamental for establishing conservation priorities, information on land use management, or even conducting further biogeographic studies.

Figure 4 .
Figure 4. a. Geographical distribution of Januaria lombardii.Coloured areas represent the distribution of three ecoregions near J. lombardii.The regionalization follows Olson's classification (2001).b.Geographical distribution of Januaria lombardii in relation to the protected areas (National Park Cavernas do Peraçu) and the protection status of the ecoregions according to Dinerstein et al. (2017).The ecoregion protection categories are defined as follows: Nature Could Recover, the sum of the amount of natural habitat remaining and the amount of the total ecoregion that is protected is less than 50% but more than 20%; Nature Imperiled, the sum of the amount of natural habitat remaining and the amount of the total ecoregion that is protected is less than or equal to 20%.

Table III .
Comparison of pollen grains features between Januaria and similar species with reticule exine of Spermacoce clade.Psyllocarpus, inhabits the Cerrado in the states of Bahia, Goiás, Minas Gerais, and the Distrito Federal; whereas P. sect.Amazonica J.H.Kirkbr. is restricted to white-sand Amazonian campinas in the states of Amazonas, Pará, and Rondônia.
Spermacoce decipiens (K.Schum.)Kuntze].Corolla with a fringe of trichomes internally on the inferior half of the corolla lobes or in the tube.Stamens and style included.Seeds 2 per capsule [widespread].