Data ownership 

The Mussels of Texas (MoTX) and associated database are a culmination of NRI effort plus partial funding support used in the website interface from TxDOT over a 10-year period. The data itself comes from a variety of sources including museums, state agencies, academia, and private companies. These data in turn have been QA/QC and georeferenced to ensure their accuracy. Despite these quality control measures, NRI cannot guarantee the validity of contributed data. MoTX, to include all content and database are under a license, and the copyrights are owned by NRI, therefore users should use the following citation whenever using content or data from this website/database other than contributed data:

Charles R. Randklev, A.H. Kiser, Clint R. Robertson, N.B. Ford, Mark Fisher, Ross Anderson, Michael Hart, Jennifer Khan and Roel Lopez. 2023. Mussels of Texas Project Database, Version 3.0.  

Data queries 

Queries allow users to construct complex personalized searches. Users may include in queries many database fields such as geography (county and basin descriptions) and taxonomy (family, genus and/or species). Users can also limit their queries to only those records within a specific buffered area – an important feature for users needing precisely georeferenced records only.

Data upload

The Mussels of Texas (MoTX) is reliant on high-quality distribution information from the public, state and federal agencies, and academia. To contribute, users would complete the database form found on the website and submit to MoTX. To access the form, users will need to register and all content/data shared will be vetted and QA/QCed by NRI staff. Because mussels can be difficult to identify, even for experienced researchers, we ask that photos vouchers, if available, be included when emailing the completed database form. 

Data Entry Form

  1. From the login page, click the data entry link.
  2. User fills in data entry form (see possible parameters below) and hits submit.
  3. Asterisks denotes required fields

Species [genus]*

Species [epithet]*

Common name

Location (description of sampling location, be specific enough to find the site)*

Drainage (major river drainage)*

Waterbody (river, stream or lake sampled)*








Identified by

Experience (years)

Source (Institution or company)

# Live*

# Fresh dead (i.e., tissue within shell)*

# Shell*

Comments (indicate condition of shell, if possible)

Gravid (Y or N)

Juveniles present (Y or N)

Juvenile size (mm)

Subadults present (Y or N)

Subadult size (mm)

Description of survey method (be specific)




Names of mussels used in this guide are those in A Revised List of the Freshwater Mussels (Mollusca: Bivalvia: Unionida) of the United States and Canada, published in 2017 by Williams et al., which comprised of a joint committee of taxonomic experts affiliated with the Freshwater Mollusk Conservation Society. In a few instances, we do not follow Williams et al. (2017) and instead present new or revised names following recent peer-reviewed literature on taxonomy and systematics within the United States. Scientific names consist of two Latinized and italicized words e.g., Amblema plicata. The first word of a species name is the genus, the second is the “specific epithet.” The author of the description and the year in which the name was first applied to the species is also presented. The author and date are surrounded by parenthesis if the species name has been moved from the genus in which it was first placed and is absent if the species remains in its original genus.

Photographs and illustrations

Multiple photographs were taken of each species presented in this guide to show the morphological variability, if present, across a given species range. Photographs show what a “typical” individual looks like for a given species from a given location. Maximum shell length (the distance between the anterior and posterior end of a shell) of a depicted individual is presented in metric units.

Species Accounts

Species accounts begin with scientific and common names followed by a photograph showing a typical individual and then information on identification, reproductive biology, ecology, and conservation status.

Type locality 

The type locality of is the geographical place of capture, collection or observation of the name-bearing type.


This section describes useful characters for identification. These can be categorized as the following: (1) shell structure – describes shell thickness and shape (i.e., outline); (2) shell color – describes the color of the periostrucum (or outside of the shell); (3) shell texture – describes the external ornamentation of the shell (e.g., pustules, ridges, ect.); (4) beaks – describes the depth and height of the beak (i.e., umbo) relative to the hinge line; (5) beak sculpture – describes ornamentation of the beak; (6) pseudocardinal teeth – the thickness and shape of the pseudocardinal and lateral teeth; (7) nacre – describes the color of the nacre, the inside of the shell, which is also known as the mother of pearl; (8) other – describes other noteworthy characters.

General range

This section describes the overall range of a given species within North America and Texas.

Range in Texas

This section is a description of a species’ specific geographic range within Texas.


Mussels vary in the habitats they occupy and the location in where they occur in a given stream system. For example, some species are habitat specialists e.g., Fusconaia mitchelli occurring in specific habitat types such as riffles, while others are more generalists, e.g., Amblema plicata occurring within a range of habitat types. Species occurrence also can vary based on stream position (i.e., headwaters vs. middle reaches vs. lower reaches), and the degree to which this occurs varies by species, the flow regime and anthropogenic impacts. For each fact sheet, a general description of the size of river a species can occur in is provided, e.g., medium-sized to large rivers, which would make the distinction between rivers like the Navasota and the Brazos. A general description of water velocity is also provided to help differentiate habitats with flowing water from those in which flow is barely perceivable or stagnant. Substrate composition of where individuals are often collected is also given in general terms, e.g., inhabits habitat with mud, sand and detritus. Remarks on whether a species can inhabit artificial waterbodies, e.g., reservoirs and canals, and ability to cope with human impacts is provided. 


Describes whether host fish are known of a given species and if so a general description of those host species.


Provides information on whether the species is a long vs. short term brooder (i.e., does it overwinter its glochidia), size of glochidia, and life-history information (longevity, fecundity, age of maturity, and threats). 


Provides information on taxonomic issues. 

Similar species

Comparisons are made with mussel species that appear similar to the species in question and diagnostic characters are provided to differentiate them.

Legal listing status

Species described as state-listed or Under Review, Candidate, or either Threatened or Endangered under the U.S. Endangered Species act follow what as either been published in the state or federal register as of May 2019.


Species Distribution Models

For each species fact sheet a range map is presented based on species distribution models (SDMs), which are an effective way to show general distributions of a given species using environmental conditions around known occurrence points and correlating those characteristics with other areas that have similar conditions.

Occurrence data were obtained from the database and then sorted into species presences datasets. Due to limitations in the temporal and spatial coverage of sampling events, pseudo-absence data was randomly generated at two times the number of known occurrences within the presumptive range of the species. Environmental variables used in modeling efforts included climate, topographic metrics, and land use/land cover.

To reduce single model bias in predictions, we utilized an ensemble method that combines the output of multiple models and multiple iterations of those models based on a weighted average that maximizes Sensitivity (correctly predicted presences) and Specificity (correctly predicted absences). These ensemble SDMs were then shown as a probability of occurrence of a species or likelihood of a species being in that area based on habitat suitability.

Known occurrence points of each species were color coded to represent the most recent sampling that occurred to identify the temporal distribution of sampling events. The resulting maps can then be used to identify range size, survey needs, and high priority areas for conservation.  


Conservation Status Map

Conservation status assessment maps are a way to efficiently determine the status of a given species and have been used in conservation assessments by U.S. Fish & Wildlife Service for rare aquatic species.  Generally, conservation maps are suitable for coarse-level assessments and are generated using occurrence data mapped at a watershed scale using GIS. The resulting map can then be used to identify range size, survey needs, and high priority areas for conservation.

For the species factsheets and both interactive maps, a conservation status maps was generated followed methods presented in the Conservation Status Map package by the Georgia Conservation Status Map package provided by the Georgia Department of Natural Resources. Occurrence data was obtained from the database and was then sorted (see below for specific categories) and graphically displayed based on date of collection and live/fresh dead (i.e., soft tissue present within the shell) vs. shell.  

Current - 2011 to present [live and/or fresh-dead] 

Recent - 1995 to 2011 [live and/or fresh-dead]

Historical - Prior to 1995 [live and/or fresh-dead]

Shell only [shell of various condition]

*categories are displayed based on date of collection. For example, if a HUC has both a "current" and "recent" collection only the "current" record will be displayed. HUCs that show "recent" or "historical" color schemes indicate that the given species has not been collected recently, which could be due to extirpation or lack of sampling.