diff --git a/R/check_eventdate.R b/R/check_eventdate.R
index 5627a08..3827516 100644
--- a/R/check_eventdate.R
+++ b/R/check_eventdate.R
@@ -45,8 +45,7 @@ check_eventdate <- function(data) {
   if (!"eventDate" %in% names(data)) {
     return(data_frame(
       level = "error",
-      message = "Column eventDate missing",
-      stringsAsFactors = FALSE
+      message = "Column eventDate missing"
     ))
   }
 
@@ -59,8 +58,7 @@ check_eventdate <- function(data) {
       level = "error",
       row = rows,
       field = "eventDate",
-      message = paste0("eventDate ", data$eventDate[rows], " does not seem to be a valid date"),
-      stringsAsFactors = FALSE
+      message = paste0("eventDate ", data$eventDate[rows], " does not seem to be a valid date")
     ))
   }
 
diff --git a/R/check_fields.R b/R/check_fields.R
index ed4ec3b..4f8f2ff 100644
--- a/R/check_fields.R
+++ b/R/check_fields.R
@@ -21,8 +21,7 @@ check_fields <- function(data, level = "error") {
         level = "error",
         field = fields,
         row = NA,
-        message = paste0("Required field ", fields, " is missing"),
-        stringsAsFactors = FALSE
+        message = paste0("Required field ", fields, " is missing")
       ))
     }
 
@@ -36,8 +35,7 @@ check_fields <- function(data, level = "error") {
             level = "error",
             field = field,
             row = which(rows),
-            message = paste0("Empty value for required field ", field),
-            stringsAsFactors = FALSE
+            message = paste0("Empty value for required field ", field)
           ))
         }
       }
@@ -54,8 +52,7 @@ check_fields <- function(data, level = "error") {
         errors <- bind_rows(errors, data_frame(
           field = fields,
           level = "warning",
-          message = paste0("Recommended field ", fields, " is missing"),
-          stringsAsFactors = FALSE
+          message = paste0("Recommended field ", fields, " is missing")
         ))
       }
 
@@ -69,8 +66,7 @@ check_fields <- function(data, level = "error") {
               level = "warning",
               field = field,
               row = which(rows),
-              message = paste0("Empty value for recommended field ", field),
-              stringsAsFactors = FALSE
+              message = paste0("Empty value for recommended field ", field)
             ))
           }
         }
diff --git a/R/check_outliers.R b/R/check_outliers.R
index de2b3ae..d3ad80e 100644
--- a/R/check_outliers.R
+++ b/R/check_outliers.R
@@ -10,7 +10,8 @@
 #'   by in order to determine the range of valid values. Default is \code{6}.
 #' @param iqr_coef Coefficient to multiply the interquartile range (IQR) by in
 #'   order to determine the range of valid values. Default values is \code{3}.
-#'
+#' @param topn Number of species for which the QC should be performed. Default
+#'   is \code{NA} (all species).
 #' @return Problematic records or an errors report.
 #' @examples
 #' \dontrun{
@@ -24,7 +25,7 @@
 #' @seealso \code{\link{plot_outliers}} \code{\link{check_outliers_dataset}}
 #'   \code{\link{check_onland}} \code{\link{check_depth}}
 #' @export
-check_outliers_species <- function(data, report = FALSE, mad_coef = 6, iqr_coef = 3) {
+check_outliers_species <- function(data, report = FALSE, mad_coef = 6, iqr_coef = 3, topn = NA) {
   errors <- check_lonlat(data, report = TRUE)
   if (!'scientificNameID' %in% colnames(data)) {
     errors <- rbind(errors, data_frame(level = 'error', message = 'Column scientificNameID missing'))
@@ -43,7 +44,12 @@ check_outliers_species <- function(data, report = FALSE, mad_coef = 6, iqr_coef
     stop(paste(errors, collapse = ", "))
   }
   result <- NULL
-  taxa <- unique(na.omit(aphiaids))
+
+  taxa <- table(na.omit(aphiaids))
+  if(!is.na(topn) & !is.null(topn) & topn > 0 & topn < length(taxa)) {
+    taxa <- sort(taxa, decreasing = TRUE)[1:topn]
+  }
+  taxa <- as.integer(names(taxa))
   for(taxon in taxa) {
     return_values = report # values are practical for creating the report
     istaxon <- !is.na(aphiaids) & aphiaids == taxon
@@ -179,9 +185,9 @@ plot_outliers_environmental <- function(outliers_info, title = '', sample_outlie
                             upper = ifelse(is.null(o$q3) || is.na(o$q3), NA, o$q3) )
       databox <- databox[complete.cases(databox),]
       datapoints <- data_frame(Statistic=c(rep('MAD', n) , rep('IQR', n)),
-                         Ok = c(o$ok_mad, o$ok_iqr),
-                         Value=rep(o$values, 2), stringsAsFactors = TRUE)
-      datapoints <- datapoints %>% filter(!is.na(Value) & (as.character(Statistic) %in% as.character(databox$Statistic)) & !Ok)
+                               Ok = c(o$ok_mad, o$ok_iqr),
+                               Value=rep(o$values, 2))
+      datapoints <- datapoints %>% filter(!is.na(Ok) & !is.na(Value) & (as.character(Statistic) %in% as.character(databox$Statistic)) & !Ok)
       if(nrow(databox) > 0 & nrow(datapoints) > 0) {
         if(!is.null(sample_outliers) & !is.na(sample_outliers) & (sample_outliers < nrow(datapoints)) & sample_outliers > 10) {
           datapoints <- sample_n(datapoints, sample_outliers)
@@ -208,15 +214,19 @@ plot_outliers_environmental <- function(outliers_info, title = '', sample_outlie
 
 plot_outliers_spatial <- function(outliers_info, title='', sample_okpoints=1000) {
   o <- outliers_info[['spatial']]
-  data <- as_data_frame(o$xy)
-  if (nrow(data[!o$ok_iqr | !o$ok_mad,]) > 0){
+  ok_na <- is.na(o$ok_iqr) | is.na(o$ok_mad)
+  ok_iqr <- o$ok_iqr[!ok_na]
+  ok_mad <- o$ok_mad[!ok_na]
+  data <- as_data_frame(o$xy[!ok_na,])
+
+  if (nrow(data[!ok_iqr | !ok_mad,]) > 0){
     okcolor <- '#1b9e77'
     data[,'color'] <- okcolor
     data[,'radius'] <- 3.5
-    data[!o$ok_iqr & o$ok_mad, 'color'] <- '#d95f02'
-    data[!o$ok_iqr & !o$ok_mad, 'color'] <- '#e7298a'
-    data[o$ok_iqr & !o$ok_mad, 'color'] <- '#7570b3'
-    data <- unique(data)
+    data[!ok_iqr & ok_mad, 'color'] <- '#d95f02'
+    data[!ok_iqr & !ok_mad, 'color'] <- '#e7298a'
+    data[ok_iqr & !ok_mad, 'color'] <- '#7570b3'
+    data <- unique(data[complete.cases(data),])
     if(!is.null(sample_okpoints) & !is.na(sample_okpoints) & sample_okpoints > 10 & nrow(data) > sample_okpoints) {
       whichok <- which(data$color == okcolor)
       if(length(whichok) > sample_okpoints) {
diff --git a/R/plot_map.R b/R/plot_map.R
index 1d82c27..ac4f464 100644
--- a/R/plot_map.R
+++ b/R/plot_map.R
@@ -8,29 +8,34 @@
 #' @export
 plot_map <- function(data, zoom = FALSE) {
   check_lonlat(data, FALSE)
-  world <- borders("world", colour="gray80", fill="gray80")
-  m <- ggplot() +
-    world +
-    geom_point(data = data, aes(x = decimalLongitude, y = decimalLatitude), size = 2, stroke = 1, alpha = 0.3, colour = "#FF368B") +
-    xlab("longitude") +
-    ylab("latitude")
+  m <- NULL
+  data <- get_xy_clean(data)
+  if(NROW(data) > 0) {
+    world <- borders("world", colour="gray80", fill="gray80")
+    m <- ggplot() +
+      world +
+      geom_point(data = data, aes(x = decimalLongitude, y = decimalLatitude), size = 2, stroke = 1, alpha = 0.3, colour = "#FF368B") +
+      xlab("longitude") +
+      ylab("latitude")
 
-  xrange <- range(data$decimalLongitude, na.rm = TRUE)
-  yrange <- range(data$decimalLatitude, na.rm = TRUE)
+    xrange <- range(data$decimalLongitude, na.rm = TRUE)
+    yrange <- range(data$decimalLatitude, na.rm = TRUE)
 
-  if (zoom & all(is.finite(xrange)) & all(is.finite(yrange))) {
-    margin <- 0.3
-    dx <- margin * (xrange[2] - xrange[1])
-    dy <- margin * (yrange[2] - yrange[1])
-    xrange[1] <- xrange[1] - dx
-    xrange[2] <- xrange[2] + dx
-    yrange[1] <- yrange[1] - dy
-    yrange[2] <- yrange[2] + dy
-    m <- m + coord_quickmap(xlim = xrange, ylim = yrange)
+    if (zoom & all(is.finite(xrange)) & all(is.finite(yrange))) {
+      margin <- 0.3
+      dx <- margin * (xrange[2] - xrange[1])
+      dy <- margin * (yrange[2] - yrange[1])
+      xrange[1] <- xrange[1] - dx
+      xrange[2] <- xrange[2] + dx
+      yrange[1] <- yrange[1] - dy
+      yrange[2] <- yrange[2] + dy
+      m <- m + coord_quickmap(xlim = xrange, ylim = yrange)
+    } else {
+      m <- m + coord_quickmap()
+    }
   } else {
-    m <- m + coord_quickmap()
+    warning("No valid coordinates found for plotting")
   }
-
   return(m)
 
 }
diff --git a/R/report.R b/R/report.R
index d81fe0a..3abf512 100644
--- a/R/report.R
+++ b/R/report.R
@@ -34,13 +34,15 @@ report_summary <- function(qcreport, maxrows) {
 #'   \code{rappdirs::user_cache_dir("obistools")}).
 #' @param view Logical, show the report in a browser after creation (default
 #'   \code{TRUE}).
+#' @param topnspecies Integer, number of species ordered by number of records
+#'   for which you want to do the outlier analysis
 #' @return Returns the full path to the generated html report.
 #' @examples
 #' \dontrun{
 #' report(abra)
 #' }
 #' @export
-report <- function(data, qc = NULL, file = "report.html", dir = NULL, view = TRUE) {
+report <- function(data, qc = NULL, file = "report.html", dir = NULL, view = TRUE, topnspecies = 20) {
 
   reportfile <- system.file("", "report.Rmd", package = "obistools")
 
@@ -51,7 +53,7 @@ report <- function(data, qc = NULL, file = "report.html", dir = NULL, view = TRU
       check_onland(data, report = TRUE),
       check_depth(data, report = TRUE),
       check_outliers_dataset(data, report = TRUE),
-      check_outliers_species(data, report = TRUE)
+      check_outliers_species(data, report = TRUE, topn = topnspecies)
     )
     qc <- distinct(qc)
   }
@@ -63,4 +65,3 @@ report <- function(data, qc = NULL, file = "report.html", dir = NULL, view = TRU
   }
   return(outputfile)
 }
-
diff --git a/R/util.R b/R/util.R
index 56f5b6a..937b01f 100644
--- a/R/util.R
+++ b/R/util.R
@@ -39,7 +39,7 @@ check_lonlat <- function(data, report) {
   }
   if(length(errors) > 0) {
     if(report) {
-      return(data.frame(level = "error",  message = errors, stringsAsFactors = FALSE))
+      return(data_frame(level = "error",  message = errors))
     } else {
       stop(paste(errors, collapse = ", "))
     }
@@ -47,30 +47,45 @@ check_lonlat <- function(data, report) {
   return(NULL)
 }
 
-get_xy_clean_duplicates <- function(data) {
+
+get_xy_clean <- function(data, returnisclean=FALSE) {
   check_lonlat(data, report = FALSE)
+  sp <- data.frame(decimalLongitude = numeric(0), decimalLatitude = numeric(0))
+  isclean <- NULL
   if(NROW(data) > 0) {
     sp <- data %>% select(decimalLongitude, decimalLatitude)
-    # Only lookup values for valid coordinates
+    # Only valid coordinates
     isclean <- stats::complete.cases(sp) &
       sapply(sp$decimalLongitude, is.numeric) &
       sapply(sp$decimalLatitude, is.numeric) &
       !is.na(sp$decimalLongitude) & !is.na(sp$decimalLatitude) &
       sp$decimalLongitude >= -180.0 & sp$decimalLongitude <= 180.0 &
       sp$decimalLatitude >= -90.0 & sp$decimalLatitude <= 90.0
-    cleansp <- sp[isclean,,drop=FALSE]
+  }
+  cleansp <- sp[isclean,,drop=FALSE]
+  if(returnisclean) {
+    return(list(cleansp=cleansp, isclean=isclean))
+  } else {
+    return(cleansp)
+  }
+}
+
+get_xy_clean_duplicates <- function(data) {
+  clean <- get_xy_clean(data, returnisclean = TRUE)
+  if(NROW(clean$cleansp) > 0) {
     # Only lookup values for unique coordinates
-    key <- paste(cleansp$decimalLongitude, cleansp$decimalLatitude, sep='\r')
+    key <- paste(clean$cleansp$decimalLongitude, clean$cleansp$decimalLatitude, sep='\r')
     notdup <- !duplicated(key)
-    uniquesp <- cleansp[notdup,]
+    uniquesp <- clean$cleansp[notdup,]
     duplicated_lookup <- match(key, key[notdup])
-    list(uniquesp=uniquesp, isclean=isclean, duplicated_lookup=duplicated_lookup)
+    list(uniquesp=uniquesp, isclean=clean$isclean, duplicated_lookup=duplicated_lookup)
   } else {
     list(uniquesp = data.frame(decimalLongitude = numeric(0), decimalLatitude = numeric(0)),
          isclean = NULL, duplicated_lookup = NULL)
   }
 }
 
+
 list_cache <- function() {
   list.files(rappdirs::user_cache_dir("obistools"), "call_", full.names = TRUE)
 }
@@ -89,7 +104,7 @@ cache_call <- function(key, expr, env = NULL) {
   }
   cache_dir <- rappdirs::user_cache_dir("obistools")
   cachefile <- file.path(cache_dir, paste0("call_", digest::digest(list(key=key, expr=expr)), ".rds"))
-  if(file.exists(cachefile) && difftime(Sys.time(), file.info(cachefile)[,"mtime"], units = "hours") < 36) {
+  if(file.exists(cachefile) && difftime(Sys.time(), file.info(cachefile)[,"mtime"], units = "hours") < 10) {
     return(readRDS(cachefile))
   } else {
     result <- eval(expr, envir = NULL, enclos = env)
diff --git a/man/check_outliers_species.Rd b/man/check_outliers_species.Rd
index c514bfd..afa59c8 100644
--- a/man/check_outliers_species.Rd
+++ b/man/check_outliers_species.Rd
@@ -18,6 +18,9 @@ by in order to determine the range of valid values. Default is \code{6}.}
 
 \item{iqr_coef}{Coefficient to multiply the interquartile range (IQR) by in
 order to determine the range of valid values. Default values is \code{3}.}
+
+\item{topn}{Number of species for which the QC should be performed. Default
+is \code{NA} (all species).}
 }
 \value{
 Problematic records or an errors report.
diff --git a/man/report.Rd b/man/report.Rd
index 98357d4..09823be 100644
--- a/man/report.Rd
+++ b/man/report.Rd
@@ -4,7 +4,8 @@
 \alias{report}
 \title{Creates a basic data quality report.}
 \usage{
-report(data, qc = NULL, file = "report.html", dir = NULL, view = TRUE)
+report(data, qc = NULL, file = "report.html", dir = NULL, view = TRUE,
+  topnspecies = 20)
 }
 \arguments{
 \item{data}{The data frame.}
@@ -19,6 +20,9 @@ data.}
 
 \item{view}{Logical, show the report in a browser after creation (default
 \code{TRUE}).}
+
+\item{topnspecies}{Integer, number of species ordered by number of records
+for which you want to do the outlier analysis}
 }
 \value{
 Returns the full path to the generated html report.